백준알고리즘 2839번 java

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner1 = new Scanner(System.in);
        int three, five;
        int num = scanner1.nextInt();
        five = num / 5;
        three = num % 5 / 3;
        if (num == (five * 5) + (three * 3))
            System.out.println(five + three);
        else {
            while (num != (five * 5) + (three * 3)) {
                five--;
                int temp = num;
                temp -= (five * 5);
                if (five > 0)
                    three = temp / 3;
                else
                    three = temp / 3;
            }
            if((five<0) || (three <0))
                System.out.println("-1");
            else
                System.out.println(three+five);
        }
    }
}