#include<bits/stdc++.h>
using namespace std;
typedef pair<int,int>p;
int n,hp,a[100010],b[100010];
priority_queue<p>q;
int main()
{
	int ans=0;
	scanf("%d%d",&n,&hp);
	for(int i=1;i<=n;i++) scanf("%d%d",&a[i],&b[i]);
	for(int i=1;i<=n;i++){
		if(hp>a[i]){
			hp=hp-a[i]+b[i];
			q.push({a[i],b[i]});
		}
		else{
			ans++;
			int k=a[i];
			if(q.empty()) hp+=b[i];
			else if(q.top().first>k||q.top().first==k&&q.top().second>b[i]){
				hp+=q.top().first;
				q.pop();
				hp=hp-a[i]+b[i];
				q.push({a[i],b[i]});
			}
			else hp+=b[i];
		}
	}
	printf("%d",ans);
	return 0;
}