RT

#include<bits/stdc++.h>
using namespace std;
struct node{
	int x,y;
} k[105];
bool cmp(node n,node m){
    return n.x>=m.x;
}
int sum=0;
int main(){
	long long n,s,a,b;
	cin>>n>>s>>a>>b;
	a+=b;
	for(int i=1;i<=n;i++){
		cin>>k[i].x>>k[i].y;
	}
	sort(k+1,k+n+1,cmp);
	for(int i=1;i<=n;i++){
		if(k[i].x<=a&&s-k[i].y>=0){
			sum++;
			s-=k[i].y;
		}
	}
	cout<<sum;
    return 0;
}