救急，only 40pts

#include <bits/stdc++.h>
using namespace std;
int n,x;
int chair,arm;
int ans = 0;
struct tt{
    int gd;
    int shlq;
}aple[10000];
bool cmp(tt a,tt b){
    a.gd < b.gd && a.shlq < b.shlq;
}
int main(){
    cin >> n >> x;
    cin >> arm >> chair;
    for(int i = 1;i <= n;i++){
        cin >> aple[i].gd >> aple[i].shlq;
    }
    sort(aple + 1,aple + n + 1,cmp);
    for(int i = 1;i <= n;i++){
        if(arm + chair >= aple[i].gd && x >= aple[i].shlq){
            ans++;
            x -= aple[i].shlq;
        }
    }
    cout << ans;
    return 0;
}