我裂开了求大佬debug

#include<iostream>
#include<cmath>
#include<algorithm>

using namespace std;

struct node{
    int x;
    int y;
}u[5010];

bool cmp(node a,node b)
{
    return a.y<b.y;
}

int main()
{
    int n,s,a,b,idx=0,sum=0,k;
    cin >> n >> s >> a >> b;
    while(n--)
    {
        int x,y;
        cin >> x >> y;
        if(x<=a+b)
        {
            u[idx].x=x;
            u[idx].y=y;
            idx++;
        }
    }
    sort(u,u+idx,cmp);
    for(int i=0;i<idx;i++)
    {
        sum+=u[i].y;
        if(sum<=s)
        {
            k++;
         } 

    }
    cout << k << endl;
    return 0;
 } 

蟹蟹各位啦