#include<bits/stdc++.h>

using namespace std;


struct a{
	int gr;
	int pr;
};

int n,g,s,gre;
a r[5100];

bool comp(a l,a r){
	return (l.pr>r.pr);
}

int main(){
	ifstream cin("rucsac.in");
	ofstream cout("rucsac.out");
	cin>>n>>g;
	for(int i=1;i<=n;i++){
		cin>>r[i].gr>>r[i].pr;
	}
	sort(r+1,r+n+1,comp);
	
	int i=1;
	while(gre<g){
		s+=r[i].pr;
		//cout<<s<<" ";
		gre+=r[i].gr;
		//cout<<gre<<'\n';
		i++;
	}
	cout<<s;
	return 0;
}