题解 | #搬圆桌#

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextInt()) {
            int r = sc.nextInt();
            int x = sc.nextInt();
            int y = sc.nextInt();
            int x1 = sc.nextInt();
            int y1 = sc.nextInt();
            double dis = Math.sqrt(Math.pow(x1 - x, 2) + Math.pow(y1 - y, 2));
            double cnt = dis / r / 2;
            System.out.println((int)Math.ceil(cnt));
        }
    }
}