#include <fstream>

using namespace std;

struct Generatoare
{
	int e, c;
};
Generatoare a[1001];

int b[1001];

int main()
{
	int g, w;
	ifstream f ("energii.in");
	f>>g>>w;
	int i;
	for (i=0; i<g; i++)
		f>>a[i].e>>a[i].c;
	f.close();
	int cost=-1, j, sumae, sumac;
	
	while (!b[g])
	{
		b[0]++;
		j=0;
		while (b[j]==2)
		{
			b[j]=0;
			b[++j]++;
		}
		sumae=sumac=0;
		for (i=0; i<j+1; i++)
			if (b[i])
			{
				sumae+=a[i].e;
				sumac+=a[i].c;
			}
		if (!b[g])
		if (sumae>=w)
			cost=(sumac>cost)?sumac:cost;
	}
	ofstream gica ("energii.out");
	gica<<cost<<"\n";
	gica.close();
	
	return 0;
}