#include <fstream>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
int eg[1003],cg[1003],i,j,Gn,W,cost[10003];
int main()
{
    f>>Gn>>W;
    for (i=1; i<=Gn; i++)f>>eg[i]>>cg[i];
    for (i=1; i<=W+5000; i++) cost[i]=100000000;
    cost[0]=0;
    for(i=1; i<=Gn; i++)
     for (j=W+5000; j>=eg[i]; j--)
       if(cost[j]>cost[j-eg[i]]+cg[i])cost[j]=cost[j-eg[i]]+cg[i];
    while(cost[W]==100000000)W++;
    g<<cost[W]<<'\n';
    return 0;
}