#include<bits/stdc++.h>
using namespace std;
struct taotao{
	int x,y;
};
taotao a[10010];
int n,s,b,c,ans;
bool cmp(taotao x,taotao y)
{
	if(x.y<y.y) return 1;
	if(x.y>y.y) return 0;
}
int main()
{
	cin>>n>>s>>b>>c;
	c+=b;
	for(int i=1;i<=n;i++) cin>>a[i].x>>a[i].y;
	sort(a+1,a+n+1,cmp);
	for(int i=1;i<=n;i++)
	{
		if(a[i].x<=c && s>=a[i].y)
		{
			ans+=1;
			s-=a[i].y;
		}
	}
	cout<<ans;
	return 0;
}

如上，WA了#3和#5