#include <bits/stdc++.h>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
const int Inf = 0x3f3f3f3f;
int v[10001], n, G, m, c, i, j;
int main()
{
    f >> n >> G;
    for(i = 1; i <= G; i ++)
        v[i] = Inf;
    for(i = 1; i <= n; i ++)
    {
        f >> c >> m;
        for(j = G; j >= 0; j --)
            {
                if(j > c) v[j] = min(v[j - c] + m, v[j]);
                        else v[j] = min(v[j], m);
            }
    }
    if(v[G] == Inf) g << -1;
                    else g << v[G];
  return 0;
}