Amr loves Geometry. One day he came up with a very interesting problem.

Amr has a circle of radius r and center in point (x, y). He wants the circle center to be in new position (x', y').

In one step Amr can put a pin to the border of the circle in a certain point, then rotate the circle around that pin by any angle and finally remove the pin.

Help Amr to achieve his goal in minimum number of steps.

Input

Input consists of 5 space-separated integers r, x, y, x' y' (1 ≤ r ≤ 105,  - 105 ≤ x, y, x', y' ≤ 105), circle radius, coordinates of original center of the circle and coordinates of destination center of the circle respectively.

Output

Output a single integer — minimum number of steps required to move the center of the circle to the destination point.

Examples

Input

2 0 0 0 4


Output

1


Input

1 1 1 4 4


Output

3


Input

4 5 6 5 6


Output

0

Note

In the first sample test the optimal way is to put a pin at point (0, 2) and rotate the circle by 180 degrees counter-clockwise (or clockwise, no matter).

<image>
/* package codechef; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;
import static java.lang.Math.*;

/* Name of the class has to be "Main" only if the class is public. */
// class Codeche
public class AmrandPins
{
    static InputReader in = new InputReader(System.in);
    static OutputWriter out = new OutputWriter(System.out);

    public static void main(String[] args) throws java.lang.Exception {

        int r = in.nextInt();
        int x1 = in.nextInt();
        int y1 = in.nextInt();
        int x2 = in.nextInt();
        int y2 = in.nextInt();
        
        long x = x2-x1;
        long y = y2-y1;
        double dis = Math.sqrt(x*x+y*y);

        double ans;
        if(dis%(r*2) == 0){
            ans = dis/(r*2);
        }else{
            ans = (dis/(r*2))+1;
        }

        out.printLine((int)ans);

        // in.close();
        out.flush();
        out.close();
    }

    private static class InputReader implements AutoCloseable {

        private static final int DEFAULT_BUFFER_SIZE = 1 << 16;


        private static final InputStream DEFAULT_STREAM = System.in;

        private static final int MAX_DECIMAL_PRECISION = 21;

        private int c;

        private final byte[] buf;
        private final int bufferSize;
        private int bufIndex;
        private int numBytesRead;

        private final InputStream stream;

        private static final byte EOF = -1;

        private static final byte NEW_LINE = 10;

        private static final byte SPACE = 32;

        private static final byte DASH = 45;

        private static final byte DOT = 46;
        private char[] charBuffer;
        private static final byte[] bytes = new byte[58];
        private static final int[] ints = new int[58];
        private static final char[] chars = new char[128];

        static {
            char ch = ' ';
            int value = 0;
            byte _byte = 0;
            for (int i = 48; i < 58; i++)
                bytes[i] = _byte++;
            for (int i = 48; i < 58; i++)
                ints[i] = value++;
            for (int i = 32; i < 128; i++)
                chars[i] = ch++;
        }
        private static final double[][] doubles = {
                { 0.0d, 0.00d, 0.000d, 0.0000d, 0.00000d, 0.000000d, 0.0000000d, 0.00000000d, 0.000000000d,
                        0.0000000000d, 0.00000000000d, 0.000000000000d, 0.0000000000000d, 0.00000000000000d,
                        0.000000000000000d, 0.0000000000000000d, 0.00000000000000000d, 0.000000000000000000d,
                        0.0000000000000000000d, 0.00000000000000000000d, 0.000000000000000000000d },
                { 0.1d, 0.01d, 0.001d, 0.0001d, 0.00001d, 0.000001d, 0.0000001d, 0.00000001d, 0.000000001d,
                        0.0000000001d, 0.00000000001d, 0.000000000001d, 0.0000000000001d, 0.00000000000001d,
                        0.000000000000001d, 0.0000000000000001d, 0.00000000000000001d, 0.000000000000000001d,
                        0.0000000000000000001d, 0.00000000000000000001d, 0.000000000000000000001d },
                { 0.2d, 0.02d, 0.002d, 0.0002d, 0.00002d, 0.000002d, 0.0000002d, 0.00000002d, 0.000000002d,
                        0.0000000002d, 0.00000000002d, 0.000000000002d, 0.0000000000002d, 0.00000000000002d,
                        0.000000000000002d, 0.0000000000000002d, 0.00000000000000002d, 0.000000000000000002d,
                        0.0000000000000000002d, 0.00000000000000000002d, 0.000000000000000000002d },
                { 0.3d, 0.03d, 0.003d, 0.0003d, 0.00003d, 0.000003d, 0.0000003d, 0.00000003d, 0.000000003d,
                        0.0000000003d, 0.00000000003d, 0.000000000003d, 0.0000000000003d, 0.00000000000003d,
                        0.000000000000003d, 0.0000000000000003d, 0.00000000000000003d, 0.000000000000000003d,
                        0.0000000000000000003d, 0.00000000000000000003d, 0.000000000000000000003d },
                { 0.4d, 0.04d, 0.004d, 0.0004d, 0.00004d, 0.000004d, 0.0000004d, 0.00000004d, 0.000000004d,
                        0.0000000004d, 0.00000000004d, 0.000000000004d, 0.0000000000004d, 0.00000000000004d,
                        0.000000000000004d, 0.0000000000000004d, 0.00000000000000004d, 0.000000000000000004d,
                        0.0000000000000000004d, 0.00000000000000000004d, 0.000000000000000000004d },
                { 0.5d, 0.05d, 0.005d, 0.0005d, 0.00005d, 0.000005d, 0.0000005d, 0.00000005d, 0.000000005d,
                        0.0000000005d, 0.00000000005d, 0.000000000005d, 0.0000000000005d, 0.00000000000005d,
                        0.000000000000005d, 0.0000000000000005d, 0.00000000000000005d, 0.000000000000000005d,
                        0.0000000000000000005d, 0.00000000000000000005d, 0.000000000000000000005d },
                { 0.6d, 0.06d, 0.006d, 0.0006d, 0.00006d, 0.000006d, 0.0000006d, 0.00000006d, 0.000000006d,
                        0.0000000006d, 0.00000000006d, 0.000000000006d, 0.0000000000006d, 0.00000000000006d,
                        0.000000000000006d, 0.0000000000000006d, 0.00000000000000006d, 0.000000000000000006d,
                        0.0000000000000000006d, 0.00000000000000000006d, 0.000000000000000000006d },
                { 0.7d, 0.07d, 0.007d, 0.0007d, 0.00007d, 0.000007d, 0.0000007d, 0.00000007d, 0.000000007d,
                        0.0000000007d, 0.00000000007d, 0.000000000007d, 0.0000000000007d, 0.00000000000007d,
                        0.000000000000007d, 0.0000000000000007d, 0.00000000000000007d, 0.000000000000000007d,
                        0.0000000000000000007d, 0.00000000000000000007d, 0.000000000000000000007d },
                { 0.8d, 0.08d, 0.008d, 0.0008d, 0.00008d, 0.000008d, 0.0000008d, 0.00000008d, 0.000000008d,
                        0.0000000008d, 0.00000000008d, 0.000000000008d, 0.0000000000008d, 0.00000000000008d,
                        0.000000000000008d, 0.0000000000000008d, 0.00000000000000008d, 0.000000000000000008d,
                        0.0000000000000000008d, 0.00000000000000000008d, 0.000000000000000000008d },
                { 0.9d, 0.09d, 0.009d, 0.0009d, 0.00009d, 0.000009d, 0.0000009d, 0.00000009d, 0.000000009d,
                        0.0000000009d, 0.00000000009d, 0.000000000009d, 0.0000000000009d, 0.00000000000009d,
                        0.000000000000009d, 0.0000000000000009d, 0.00000000000000009d, 0.000000000000000009d,
                        0.0000000000000000009d, 0.00000000000000000009d, 0.000000000000000000009d } };

        public InputReader() {
            this(DEFAULT_STREAM, DEFAULT_BUFFER_SIZE);
        }
        public InputReader(int bufferSize) {
            this(DEFAULT_STREAM, bufferSize);
        }
        public InputReader(InputStream stream) {
            this(stream, DEFAULT_BUFFER_SIZE);
        }
        public InputReader(InputStream stream, int bufferSize) {
            if (stream == null || bufferSize <= 0)
                throw new IllegalArgumentException();
            buf = new byte[bufferSize];
            charBuffer = new char[128];
            this.bufferSize = bufferSize;
            this.stream = stream;
        }
        private byte read() throws IOException {

            if (numBytesRead == EOF)
                throw new IOException();

            if (bufIndex >= numBytesRead) {
                bufIndex = 0;
                numBytesRead = stream.read(buf);
                if (numBytesRead == EOF)
                    return EOF;
            }

            return buf[bufIndex++];
        }
        private int readJunk(int token) throws IOException {

            if (numBytesRead == EOF)
                return EOF;
            do {

                while (bufIndex < numBytesRead) {
                    if (buf[bufIndex] > token)
                        return 0;
                    bufIndex++;
                }
                numBytesRead = stream.read(buf);
                if (numBytesRead == EOF)
                    return EOF;
                bufIndex = 0;

            } while (true);

        }
        public byte nextByte() throws IOException {
            return (byte) nextInt();
        }
        public int nextInt() throws IOException {

            if (readJunk(DASH - 1) == EOF)
                throw new IOException();
            int sgn = 1, res = 0;

            c = buf[bufIndex];
            if (c == DASH) {
                sgn = -1;
                bufIndex++;
            }

            do {

                while (bufIndex < numBytesRead) {
                    if (buf[bufIndex] > SPACE) {
                        res = (res << 3) + (res << 1);
                        res += ints[buf[bufIndex++]];
                    } else {
                        bufIndex++;
                        return res * sgn;
                    }
                }
                numBytesRead = stream.read(buf);
                if (numBytesRead == EOF)
                    return res * sgn;
                bufIndex = 0;

            } while (true);

        }
        public long nextLong() throws IOException {

            if (readJunk(DASH - 1) == EOF)
                throw new IOException();
            int sgn = 1;
            long res = 0L;
            c = buf[bufIndex];
            if (c == DASH) {
                sgn = -1;
                bufIndex++;
            }

            do {

                while (bufIndex < numBytesRead) {
                    if (buf[bufIndex] > SPACE) {
                        res = (res << 3) + (res << 1);
                        res += ints[buf[bufIndex++]];
                    } else {
                        bufIndex++;
                        return res * sgn;
                    }
                }
                numBytesRead = stream.read(buf);
                if (numBytesRead == EOF)
                    return res * sgn;
                bufIndex = 0;

            } while (true);

        }
        private void doubleCharBufferSize() {
            char[] newBuffer = new char[charBuffer.length << 1];
            for (int i = 0; i < charBuffer.length; i++)
                newBuffer[i] = charBuffer[i];
            charBuffer = newBuffer;
        }
        public String nextLine() throws IOException {

            try {
                c = read();
            } catch (IOException e) {
                return null;
            }
            if (c == NEW_LINE)
                return ""; // Empty line
            if (c == EOF)
                return null; // EOF

            int i = 0;
            charBuffer[i++] = (char) c;

            do {

                while (bufIndex < numBytesRead) {
                    if (buf[bufIndex] != NEW_LINE) {
                        if (i == charBuffer.length)
                            doubleCharBufferSize();
                        charBuffer[i++] = (char) buf[bufIndex++];
                    } else {
                        bufIndex++;
                        return new String(charBuffer, 0, i);
                    }
                }

                // Reload buffer
                numBytesRead = stream.read(buf);
                if (numBytesRead == EOF)
                    return new String(charBuffer, 0, i);
                bufIndex = 0;

            } while (true);

        }
        public String nextString() throws IOException {
            if (numBytesRead == EOF)
                return null;
            if (readJunk(SPACE) == EOF)
                return null;

            for (int i = 0;;) {
                while (bufIndex < numBytesRead) {
                    if (buf[bufIndex] > SPACE) {
                        if (i == charBuffer.length)
                            doubleCharBufferSize();
                        charBuffer[i++] = (char) buf[bufIndex++];
                    } else {
                        bufIndex++;
                        return new String(charBuffer, 0, i);
                    }
                }

                // Reload buffer
                numBytesRead = stream.read(buf);
                if (numBytesRead == EOF)
                    return new String(charBuffer, 0, i);
                bufIndex = 0;
            }
        }
        public double nextDouble() throws IOException {
            String doubleVal = nextString();
            if (doubleVal == null)
                throw new IOException();
            return Double.valueOf(doubleVal);
        }
        public double nextDoubleFast() throws IOException {
            c = read();
            int sgn = 1;
            while (c <= SPACE)
                c = read(); 
            if (c == DASH) {
                sgn = -1;
                c = read();
            }
            double res = 0.0;
            while (c > DOT) {
                res *= 10.0;
                res += ints[c];
                c = read();
            }
            if (c == DOT) {
                int i = 0;
                c = read();
                while (c > SPACE && i < MAX_DECIMAL_PRECISION) {
                    res += doubles[ints[c]][i++];
                    c = read();
                }
            }
            return res * sgn;
        }
        public byte[] nextByteArray(int n) throws IOException {
            byte[] ar = new byte[n];
            for (int i = 0; i < n; i++)
                ar[i] = nextByte();
            return ar;
        }
        public int[] nextIntArray(int n) throws IOException {
            int[] ar = new int[n];
            for (int i = 0; i < n; i++)
                ar[i] = nextInt();
            return ar;
        }
        public long[] nextLongArray(int n) throws IOException {
            long[] ar = new long[n];
            for (int i = 0; i < n; i++)
                ar[i] = nextLong();
            return ar;
        }
        public double[] nextDoubleArray(int n) throws IOException {
            double[] ar = new double[n];
            for (int i = 0; i < n; i++)
                ar[i] = nextDouble();
            return ar;
        }
        public double[] nextDoubleArrayFast(int n) throws IOException {
            double[] ar = new double[n];
            for (int i = 0; i < n; i++)
                ar[i] = nextDoubleFast();
            return ar;
        }
        public String[] nextStringArray(int n) throws IOException {
            String[] ar = new String[n];
            for (int i = 0; i < n; i++) {
                String str = nextString();
                if (str == null)
                    throw new IOException();
                ar[i] = str;
            }
            return ar;
        }
        public byte[] nextByteArray1(int n) throws IOException {
            byte[] ar = new byte[n + 1];
            for (int i = 1; i <= n; i++)
                ar[i] = nextByte();
            return ar;
        }
        public int[] nextIntArray1(int n) throws IOException {
            int[] ar = new int[n + 1];
            for (int i = 1; i <= n; i++)
                ar[i] = nextInt();
            return ar;
        }
        public long[] nextLongArray1(int n) throws IOException {
            long[] ar = new long[n + 1];
            for (int i = 1; i <= n; i++)
                ar[i] = nextLong();
            return ar;
        }
        public double[] nextDoubleArray1(int n) throws IOException {
            double[] ar = new double[n + 1];
            for (int i = 1; i <= n; i++)
                ar[i] = nextDouble();
            return ar;
        }
        public double[] nextDoubleArrayFast1(int n) throws IOException {
            double[] ar = new double[n + 1];
            for (int i = 1; i <= n; i++)
                ar[i] = nextDoubleFast();
            return ar;
        }
        public String[] nextStringArray1(int n) throws IOException {
            String[] ar = new String[n + 1];
            for (int i = 1; i <= n; i++)
                ar[i] = nextString();
            return ar;
        }
        public byte[][] nextByteMatrix(int rows, int cols) throws IOException {
            byte[][] matrix = new byte[rows][cols];
            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                    matrix[i][j] = nextByte();
            return matrix;
        }
        public int[][] nextIntMatrix(int rows, int cols) throws IOException {
            int[][] matrix = new int[rows][cols];
            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                    matrix[i][j] = nextInt();
            return matrix;
        }
        public long[][] nextLongMatrix(int rows, int cols) throws IOException {
            long[][] matrix = new long[rows][cols];
            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                    matrix[i][j] = nextLong();
            return matrix;
        }
        public double[][] nextDoubleMatrix(int rows, int cols) throws IOException {
            double[][] matrix = new double[rows][cols];
            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                    matrix[i][j] = nextDouble();
            return matrix;
        }
        public double[][] nextDoubleMatrixFast(int rows, int cols) throws IOException {
            double[][] matrix = new double[rows][cols];
            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                    matrix[i][j] = nextDoubleFast();
            return matrix;
        }
        public String[][] nextStringMatrix(int rows, int cols) throws IOException {
            String[][] matrix = new String[rows][cols];
            for (int i = 0; i < rows; i++)
                for (int j = 0; j < cols; j++)
                    matrix[i][j] = nextString();
            return matrix;
        }
        public byte[][] nextByteMatrix1(int rows, int cols) throws IOException {
            byte[][] matrix = new byte[rows + 1][cols + 1];
            for (int i = 1; i <= rows; i++)
                for (int j = 1; j <= cols; j++)
                    matrix[i][j] = nextByte();
            return matrix;
        }
        public int[][] nextIntMatrix1(int rows, int cols) throws IOException {
            int[][] matrix = new int[rows + 1][cols + 1];
            for (int i = 1; i <= rows; i++)
                for (int j = 1; j <= cols; j++)
                    matrix[i][j] = nextInt();
            return matrix;
        }
        public long[][] nextLongMatrix1(int rows, int cols) throws IOException {
            long[][] matrix = new long[rows + 1][cols + 1];
            for (int i = 1; i <= rows; i++)
                for (int j = 1; j <= cols; j++)
                    matrix[i][j] = nextLong();
            return matrix;
        }
        public double[][] nextDoubleMatrix1(int rows, int cols) throws IOException {
            double[][] matrix = new double[rows + 1][cols + 1];
            for (int i = 1; i <= rows; i++)
                for (int j = 1; j <= cols; j++)
                    matrix[i][j] = nextDouble();
            return matrix;
        }
        public double[][] nextDoubleMatrixFast1(int rows, int cols) throws IOException {
            double[][] matrix = new double[rows + 1][cols + 1];
            for (int i = 1; i <= rows; i++)
                for (int j = 1; j <= cols; j++)
                    matrix[i][j] = nextDoubleFast();
            return matrix;
        }
        public String[][] nextStringMatrix1(int rows, int cols) throws IOException {
            String[][] matrix = new String[rows + 1][cols + 1];
            for (int i = 1; i <= rows; i++)
                for (int j = 1; j <= cols; j++)
                    matrix[i][j] = nextString();
            return matrix;
        }
        public void close() throws IOException {
            stream.close();
        }

    }

    private static class OutputWriter implements AutoCloseable {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void print(Object... objects) {
            for (int i = 0; i < objects.length; i++) {
                if (i != 0)
                    writer.print(' ');
                writer.print(objects[i]);
            }
        }

        public void printLine(Object... objects) {
            print(objects);
            writer.println();
        }

        public void close() {
            writer.close();
        }

        public void flush() {
            writer.flush();
        }

    }
}
