题解

#include<iostream>
#include<queue>
using namespace std;
struct music{
	int a,b;
}c[110];
int main(){
	priority_queue<int> q;
	int n,m;
	cin>>n>>m;
	int sum = 0; 
	int cnt=0;
	for(int i=0;i<n;i++){
		cin>>c[i].a>>c[i].b;
		q.push(c[i].a-c[i].b);
		sum+=c[i].a;
	}
	while(sum>m && !q.empty()){
		sum-=q.top();
		q.pop();
		cnt++; 
	}
	if(sum<=m) cout<<cnt;
	else{
		cout<<"-1";
	}
	return 0;
}