P1478陶陶摘苹果

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
struct node{
	int x;
	int y;
}z[5001];
int cmp(node a,node b){
	return a.y<b.y;
}
int main(){
	int n,s,a,b,sum=0,ans=0;
	cin>>n>>s>>a>>b;
	for(int i=1;i<=n;i++)
	{
		cin>>z[i].x>>z[i].y;
	}
	sort(z+1,z+n+1,cmp);
	for(int i=1;i<=n;i++)
	{
		if((a+b)<=z[i].x) 
		{
			sum++;
			ans+=z[i].y;	
			if((s-ans)<z[i+1].y) break;
		}
	}
	cout<<sum<<endl;
	return 0;
}