#include <fstream>

using namespace std;

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

const int max_size = 1e3 + 1, max_dp = 1e4 + 1, INF = 1e9 + 1;

int sol[max_dp], p[max_size], e[max_size];

int main ()
{
    for (int i = 1; i < max_dp; i++)
    {
        sol[i] = INF;
    }
    int n, g;
    in >> n >> g;
    for (int i = 1; i <= n; i++)
    {
        in >> e[i] >> p[i];
    }
    for (int i = 1; i <= n; i++)
    {
        for (int j = g - e[i]; j >= 0; j--)
        {
            if (sol[j + e[i]] > sol[j] + p[i])
            {
                sol[j + e[i]] = sol[j] + p[i];
            }
        }
    }
    if (sol[g] == INF)
    {
        sol[g] = -1;
    }
    out << sol[g];
    in.close();
    out.close();
    return 0;
}