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).

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import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.StringTokenizer;

public class Main {

  public static void main(String[] args) throws IOException {
    IOScanner scanner;
    if (new File("data.in").exists()) {
      scanner = new IOScanner("data.in", null);
    } else {
      scanner = new IOScanner();
    }
    while (scanner.hasNext()) {
      new Solver(scanner).solve();
    }
    scanner.close();
  }
}

class IOScanner {
  private final BufferedReader reader;
  private final PrintWriter writer;
  private StringTokenizer stringTokenizer;

  public IOScanner() {
    this(System.in, System.out);
  }

  public IOScanner(String input, String output) throws FileNotFoundException {
    this(input == null ? null : new File(input), output == null ? null : new File(output));
  }

  public IOScanner(File input, File output) throws FileNotFoundException {
    this(input == null ? System.in : new FileInputStream(input), output == null ? System.out
        : new FileOutputStream(output));
  }

  public IOScanner(InputStream inputStream, OutputStream outputStream) {
    reader = new BufferedReader(new InputStreamReader(inputStream));
    writer = new PrintWriter(outputStream);
  }

  private StringTokenizer read() {
    while (stringTokenizer == null || !stringTokenizer.hasMoreTokens()) {
      try {
        stringTokenizer = new StringTokenizer(reader.readLine());
      } catch (Exception e) {
        return null;
      }
    }
    return stringTokenizer;
  }

  public boolean hasNext() {
    StringTokenizer tokenizer = read();
    return tokenizer != null && tokenizer.hasMoreTokens();
  }

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

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

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

  public int[] nextInts(int n) {
    int[] input = new int[n];
    for (int i = 0; i < n; i++) {
      input[i] = nextInt();
    }
    return input;
  }

  public double[] nextDoubles(int n) {
    double[] input = new double[n];
    for (int i = 0; i < n; i++) {
      input[i] = nextDouble();
    }
    return input;
  }

  public String[] nexts(int n) {
    String[] input = new String[n];
    for (int i = 0; i < n; i++) {
      input[i] = next();
    }
    return input;
  }

  public char[][] nextCharArrays(int n) {
    String[] input = nexts(n);
    char[][] result = new char[n][];
    for (int i = 0; i < n; i++) {
      result[i] = input[i].toCharArray();
    }
    return result;
  }

  public String next() {
    return read().nextToken();
  }

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

  public void println(Iterable<?> iterable) {
    println(iterable.iterator());
  }

  public void println(Iterator<?> iterator) {
    boolean first = true;
    while (iterator.hasNext()) {
      if (first) {
        first = false;
      } else {
        print(' ');
      }
      print(iterator.next());
    }
    println();
  }

  public void println(Object token) {
    writer.println(token);
  }

  public void print(Object token) {
    writer.print(token);
  }

  public void printf(String format, Object... args) {
    writer.printf(format, args);
  }

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

  public void close() throws IOException {
    reader.close();
    writer.close();
  }
}

class Solver {

  private final IOScanner scanner;

  public Solver(IOScanner scanner) {
    this.scanner = scanner;
  }

  public void solve() {
    double r = scanner.nextDouble();
    double[] a = scanner.nextDoubles(4);
    scanner.printf("%.0f\n", Math.ceil(
        Math.sqrt((a[0] - a[2]) * (a[0] - a[2]) + (a[1] - a[3]) * (a[1] - a[3])) / (2 * r)));
  }
}