[2839] 설탕배달

#include <stdio.h>
int main()
{
	int three, five, n; 
    
    scanf("%d", &n);
    
	five = n / 5;
	n %= 5;
    
	while (five >= 0) 
    {
		if (!(n % 3)) 
        {
			three = n / 3;
			n %= 3;
			break;
		}
		five--;
		n += 5;
	}
	printf("%d", n == 0 ? five + three : -1);
	return 0;
}