#include<fstream>
#define FOR for(i=1;i<=n-1;i++) for(j=i+1;j<=n;j++)
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
int n,w,i,j,k;
int costm,aux,s=0;;
int smax;
struct eon
{
	int wq,cost;
};
eon a[10002];
int main()
{
	f>>n>>w;
	for(i=1;i<=n;i++)
		f>>a[i].wq>>a[i].cost;
	FOR
	{
	if(a[i].wq<a[j].wq)
			{
				a[i].wq=aux;
				a[i].wq=a[j].wq;
				a[j].wq=aux;
				a[i].cost=aux;
				a[i].cost=a[j].cost;
				a[j].cost=aux;
			}
	}
	s+=a[1].wq;
	costm=a[1].cost;
	for(i=1;i<=n;i++)
		smax+=a[i].wq;
	for(i=1;i<=n;i++)
	{
		if(smax<w)
			g<<-1;
		if(s>=w)
		{
			g<<costm;
			i=n+1;
		}
		else
			s=s+a[i].wq;
	}
	return 0;
}