[백준] 2839번 : 설탕 배달 - C

https://www.acmicpc.net/problem/2839

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