为啥错了？？？

include<iostream>

include<algorithm>

using namespace std;

int i,i1;

int n,s,a,b;

int xi[100],yi[100];

int main(){

cin>>n>>s>>a>>b;
for (i=1;i<=n;i++){
    cin>>xi[n]>>yi[n];
} 
a=a+b;
for(i=1;i<=n;i++){
    if(xi[i]>=a){
        n++;
        for(i1=++i;i1<=n;i1++){
            xi[i1--]=xi[i1];
            yi[i1--]=yi[i1]; 
        } 
        n-=2;
    }
} 
sort(yi+1,yi+n+1);
for(i=1;i<=n;i++){
    bool l=false;
    s=s-yi[i];
    if(s<0){
        i--;
        l=true;
    }
    if(l) break;
} 
b=i;
cout<<b;

}