#include<fstream>
#include<algorithm>
#define INF 1000000000
using namespace std;
ifstream fi("energii.in");
ofstream fo("energii.out");
int g,w,i,j,W[10001],eg,cg,minim;
int main()
{
	for(i=1; i<=10000; i++)
		W[i]=INF;
	fi>>g>>w;
	for(i=1; i<=g; i++)
	{
		fi>>eg>>cg;
		for(j=10000-eg; j>=0; j--)
			if(W[j]!=INF)
				W[j+eg]=min(W[j+eg],W[j]+cg);
	}
	minim=INF;
	for(i=w; i<=10000; i++)
		if(W[i]<minim)
			minim=W[i];
	fo<<minim<<"\n";
	fi.close();
	fo.close();
	return 0;
}