#include <fstream>
using namespace std;

ifstream fin("energii.in");
ofstream fout("energii.out");

const int nu = 1<<30;

int main()
{
    int n, W, i, j, l;
    int cmin[2][5001]; //cmin[l][i] = costul minim de a obtine cel putin i unitati de energie cu primele k generatoare
    int w[1001], c[1001];
    fin >> n >> W;
    for (i = 1; i<=n; i++)
        fin >> w[i] >> c[i];
    for (i = 1; i<=W; i++)
        cmin[1][i] = nu;
    for (i = 1, l = 0; i<=n; i++, l = 1-l)
    {
        for (j = 1; j<w[i]; j++)
            cmin[l][j] = cmin[1-l][j];
        cmin[l][w[i]] = c[i];
        for (j = w[i]+1; j<=W; j++)
            cmin[l][j] = min(cmin[1-l][j], c[i]+cmin[1-l][j-w[i]]);
    }
    fout << cmin[1-l][W];
    return 0;
}