백준 2839 - 설탕 배달

import java.util.Scanner;
 
public class Main {
    public static void main(String args[]) {
        int n = new Scanner(System.in).nextInt();
        int three = 0, 
        int five = n / 5; 
        int n %= 5;
 
        while (five >= 0) {
            if (n % 3 == 0) {
                three = n / 3;
                n %= 3;
                break;
            }
            five--;
            n += 5;
        }
 
        if (n==0) {
           System.out.println(five + three);
        } else {
           System.out.println(-1);
        }
    }
}