不知道哪里错了！求助！ P2616 [USACO10JAN]Buying Feed, II S

#include<bits/stdc++.h>
using namespace std;
int k,e,n,x,c;
long long ans=0;
struct car{
    int sum,price;
}city[105];
bool cmp(car a,car b){
    a.price<b.price;
}
int main(){
    cin>>k>>e>>n;
    for(int i=0;i<n;i++){
        cin>>x>>city[i].sum>>c;
        city[i].price=c+(e-x);
    }
    sort(city,city+n,cmp);
    int s=0;
    for(int i=0;i<n;i++){
        if(s<k){
            ans+=city[i].price;
            s+=city[i].sum;
        }else{
            break;
        }
    }
    cout<<ans;
    return 0;
}