真的不知道哪里错了

望各位巨佬帮帮忙，磕头了 十分感谢！

#include<bits/stdc++.h>
using namespace std;

int main() {
    int xuyao_num = 0, baozhuang_num = 0, money = 0;//需要的数量、包装里铅笔的数量、包装价钱
    int a, b, c, a_need, b_need, c_need;//(a, b, c方案的)数量、方案价钱
    scanf("%d", &xuyao_num);//输入需要的数量
    for (int i = 0; i < 3; i++) {
        scanf("%d%d", &baozhuang_num, &money);//输入铅笔量和价钱
        if(i==0) {
           a = (int)(xuyao_num / baozhuang_num) + 1; 
           a_need = money * a;
        }
        if(i==1) {
            b = (int)(xuyao_num / baozhuang_num) + 1;
            b_need = money * b;
        }
        if(i==2) {
            c = (int)(xuyao_num / baozhuang_num) + 1;
            c_need = money * c;
        //三个if计算需要包装的数量和价钱
        }
    }
    if(a_need<b_need && a_need<c_need) printf("%d", a_need);//判断并输出
    if(b_need<a_need && b_need<c_need) printf("%d", b_need);
    if(c_need<a_need && c_need<b_need) printf("%d", c_need);
    return 0;
}