全WATOT

#include<bits/stdc++.h>
using namespace std;
struct node {
    int x,y;
};
node a[5010];
bool cmp (node m,node v) {
    return m.y<m.y;
}
int main (){
    int n,s,p,b;
    cin>>n>>s>>p>>b;
    for (int i=1;i<=n;i++) {
        cin>>a[i].x>>a[i].y;
    }
    sort(a+1,a+n+1,cmp);
    int ans=0;
    for (int i=i;i<=n;i++) {
        if (a[i].x<=p+b&&s-a[i].y>=0) {
            ans++;
            s-=a[i].y;
        }
    }
    cout<<ans<<endl;
return 0;
}