#include <fstream>
#define maxim 5001
#define maximg 10001

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

long G,W, Cmin;
long EG[maxim], CG[maxim];
long d[2][maximg];

int main ()
{   f>>G>>W;
    for (long i=1; i<=G; ++i)
        f>>EG[i]>>CG[i];

    for (long i=1; i<=G; ++i)
        for (long energie=0; energie<=W; ++energie) {
        if (EG[i]<=energie)
            d[i][energie]=min(d[i-1][energie], d[i-1][energie-EG[i]]+CG[i]);
        else d[i][energie]=d[i-1][energie]; }
    Cmin=d[G][W];
    g<<Cmin;

    return 0;
}