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>
import java.awt.Point;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.StringTokenizer;

import javafx.util.Pair;

public class Main {

    public static void main(String[] args) throws Exception {
        long startTime = System.nanoTime();
        solve();
        long endTime = System.nanoTime();
        err.println("Execution Time : +" + (endTime - startTime) / 1000000 + " ms");
        exit(0);
    }

    static void solve() {
        int r = in.nextInt();
        int x = in.nextInt();
        int y = in.nextInt();
        int x1 = in.nextInt();
        int y1 = in.nextInt();
        Point p1 = new Point(x, y);
        Point p2 = new Point(x1, y1);
        long dist = (long) Math.ceil(p1.distance(p2) / (2 * r));
        out.println(dist);
    }

    static <T> Pair<T, T> make_pair(T a, T b) {
        return new Pair<>(a, b);
    }

    static class StringUtils {
        static char[] constructReverseWithHash(String s) {
            char[] a = s.toCharArray();
            char[] b = ArrayUtils.reverse(s.toCharArray());
            char[] c = new char[a.length + b.length + 1];
            System.arraycopy(a, 0, c, 0, a.length);
            c[a.length] = '#';
            System.arraycopy(b, 0, c, a.length + 1, b.length);
            return c;
        }

        static String reverse(String s) {
            return constructStringFromChars(ArrayUtils.reverse(s.toCharArray()), 0, s.length());
        }

        static String constructStringFromChars(char[] d, int from, int to) {
            StringBuilder res = new StringBuilder();
            for (int i = from; i < to; i++) {
                res.append(d[i]);
            }
            return res.toString();
        }

        static String constructStringFromInts(int[] d, int from, int to) {
            StringBuilder res = new StringBuilder();
            for (int i = from; i < to; i++) {
                res.append(d[i]);
            }
            return res.toString();
        }

        static int[] prefix_function(char[] s) {
            int n = s.length;
            int[] pi = new int[n];
            for (int i = 1; i < n; i++) {
                int j = pi[i - 1];
                while (j > 0 && s[i] != s[j])
                    j = pi[j - 1];
                if (s[i] == s[j]) {
                    j++;
                }
                pi[i] = j;
            }
            return pi;
        }
    }

    static class NumberTheory {

        static ArrayList<Integer>[] getDivisors(int n) {
            ArrayList<Integer>[] d = new ArrayList[n + 1];
            for (int i = 1; i <= n; i++) {
                d[i] = new ArrayList<>();
            }
            for (int i = 1; i <= n; i++) {
                for (int j = i; j <= n; j += i) {
                    d[j].add(i);
                }
            }
            return d;
        }

        static long mod_pow(long x, long y, long MOD) {
            if (y == 0) {
                return 1;
            }
            if (y == 1) {
                return x;
            }
            long v = mod_pow(x, y / 2, MOD);
            if ((y & 1) > 0) {
                return v * v % MOD * x % MOD;
            }
            return v * v % MOD;
        }

        static int gcd(int a, int b) {
            while (b != 0) {
                int t = b;
                b = a % b;
                a = t;
            }
            return a;
        }

        //GCD Long
        static long gcd(long a, long b) {
            while (b != 0) {
                long t = b;
                b = a % b;
                a = t;
            }
            return a;
        }

    }

    static class ArrayUtils {

        static int[] reverse(int[] data) {
            int[] p = new int[data.length];
            for (int i = 0, j = data.length - 1; i < data.length; i++, j--) {
                p[i] = data[j];
            }
            return p;
        }

        static char[] reverse(char[] data) {
            char[] p = new char[data.length];
            for (int i = 0, j = data.length - 1; i < data.length; i++, j--) {
                p[i] = data[j];
            }
            return p;
        }

        static int[] MegreSort(int[] A) {
            if (A.length > 1) {
                int q = A.length / 2;
                int[] left = new int[q];
                int[] right = new int[A.length - q];
                System.arraycopy(A, 0, left, 0, q);
                System.arraycopy(A, q, right, 0, A.length - q);
                int[] left_sorted = MegreSort(left);
                int[] right_sorted = MegreSort(right);
                return Megre(left_sorted, right_sorted);
            } else {
                return A;
            }
        }

        static int[] Megre(int[] left, int[] right) {
            int[] A = new int[left.length + right.length];
            int i = 0;
            int j = 0;
            for (int k = 0; k < A.length; k++) {
                // To handle left becoming empty
                if (i == left.length && j < right.length) {
                    A[k] = right[j];
                    j++;
                    continue;
                }
                // To handle right becoming empty
                if (j == right.length && i < left.length) {
                    A[k] = left[i];
                    i++;
                    continue;
                }
                if (left[i] <= right[j]) {
                    A[k] = left[i];
                    i++;
                } else {
                    A[k] = right[j];
                    j++;
                }
            }
            return A;
        }

        static long[] MegreSort(long[] A) {
            if (A.length > 1) {
                int q = A.length / 2;
                long[] left = new long[q];
                long[] right = new long[A.length - q];
                System.arraycopy(A, 0, left, 0, q);
                System.arraycopy(A, q, right, 0, A.length - q);
                long[] left_sorted = MegreSort(left);
                long[] right_sorted = MegreSort(right);
                return Megre(left_sorted, right_sorted);
            } else {
                return A;
            }
        }

        static long[] Megre(long[] left, long[] right) {
            long[] A = new long[left.length + right.length];
            int i = 0;
            int j = 0;
            for (int k = 0; k < A.length; k++) {
                // To handle left becoming empty
                if (i == left.length && j < right.length) {
                    A[k] = right[j];
                    j++;
                    continue;
                }
                // To handle right becoming empty
                if (j == right.length && i < left.length) {
                    A[k] = left[i];
                    i++;
                    continue;
                }
                if (left[i] <= right[j]) {
                    A[k] = left[i];
                    i++;
                } else {
                    A[k] = right[j];
                    j++;
                }
            }
            return A;
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public int[] readAllInts(int n) {
            int[] p = new int[n];
            for (int i = 0; i < n; i++) {
                p[i] = in.nextInt();
            }
            return p;
        }

        public int[] readAllInts(int n, int s) {
            int[] p = new int[n + s];
            for (int i = s; i < n + s; i++) {
                p[i] = in.nextInt();
            }
            return p;
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }
    }

    static void exit(int a) {
        out.close();
        err.close();
        System.exit(a);
    }

    static InputStream inputStream = System.in;
    static OutputStream outputStream = System.out;
    static OutputStream errStream = System.err;
    static InputReader in = new InputReader(inputStream);
    static PrintWriter out = new PrintWriter(outputStream);
    static PrintWriter err = new PrintWriter(errStream);
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

}
