import java.util.Scanner;

public class B {
  public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
    int r = s.nextInt(), x = s.nextInt(), y = s.nextInt(), xf = s.nextInt(), yf = s.nextInt();

    double dist = Math.sqrt((xf - x) * (xf - x) + (yf - y) * (yf - y));

    int result = 0;
    while(dist > 3 * r) {
      dist -= 3 * r;
      result++;
    }


    if(dist >= 2 * r) {
      dist -= 2 * r;
      result++;
    }

    if(dist > 1e-5) {
      result += 2;
    }

    System.out.println(result);
  }
}