#include <fstream>
using namespace std;

ifstream f ("energii.in");
ofstream g ("energii.out");

int v[5005],a[5005];

int main()
{
	int G,E,en,cost;
	f>>G>>E;
	
	for (;G>0;G--)
	{
		f>>en>>cost;
		for (int i=E-en; i>=0; i--)
			if (v[i+en]<v[i]+cost)
			{	
				v[i+en]=v[i]+cost;
				a[i+en]=a[i]+en;
			}
	}

	if (a[E]<E)
		g<<-1;
	else g<<v[E];
	return 0;
}