20分求助

#include<bits/stdc++.h>
#define  ll long long
using namespace std;
int n,s,a,b,li[5010],qi[5010];
bool cmp(int x,int y){
    if(x>y) return x>y;
}
int main(){
//  freopen("taotao.in","r",stdin);
//  freopen("taotao.out","w",stdout);
    cin>>n>>s>>a>>b;
    for(int i=1;i<=n;i++) cin>>li[i]>>qi[i];
    int t=a+b,c=1,sum=0,bb=1;
    for(int i=1;i<=n;i++){
        if(t>=li[i]) li[c]=li[i],qi[c]=qi[i];
        c++;
    } 
    sort(qi,qi+n+1,cmp);
    while(sum<=s){
        sum+=qi[bb];
        bb++;
    } 
    cout<<bb-1;
    return 0;
}