贪心算法哪里错了？？？求大神帮助

#include<iostream>
#include<algorithm>
using namespace std;
int n,s,a,b,ans;
struct data {
    int x,y;
}t[5001];

bool cmp (data p,data q) {
    return p.y<q.y;
}

int main(){
    cin>>n>>s>>a>>b;
    for (int i=1;i<=n;i++) {
        cin>>t[i].x>>t[i].y;
    }
    sort(t+1,t+n+1,cmp);
    for (int i=1;i<=n;i++) {
        if (a+b>=t[i].x && s-t[i].y>0) {
            s-=t[i].y;
            ans++;
        }
        else  break;
    }
    cout<<ans<<endl;
    return 0;
}