import java.util.Scanner;

public class B {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int[] data = new int[5];
        for(int i = 0; i<5; i++){
            data[i] = sc.nextInt();
        }
        long dis = Math.round(Math.sqrt((data[4]-data[2])^2 + (data[3]-data[1])^2));
        System.out.println(dis/data[0]);
    }
}
