#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,many,money,s,answer;
    cin>>n;
    for(int i=1;i<4;i++){
        cin>>many>>money;
        s=n/many*money;
        if(n%many!=0)s+=money;
        if(i>=2){
           if(answer>s)answer=s;
           break;
        }
        answer=s;
    }
    cout<<answer;
    return 0;
}

哪里错了呀！！！