#include <iostream>
#include <fstream>
using namespace std;

struct generator
{
    int e, c;
}v[1005];

int n, w, cMin[1000005], wMax, minv = 1000005;

int main()
{
    ifstream cin("energii.in");
    ofstream cout("energii.out");

    fill_n(cMin, 1000005, 1000005);
    cMin[0] = 0;
    cin >> n >> w;
    for (int i = 1; i <= n; ++i)
    {
        cin >> v[i].e >> v[i].c;
        wMax += v[i].e;

        for (int j = 0; j <= wMax; ++j)
        {
            cMin[j + v[i].e] = min(cMin[j + v[i].e], cMin[j] + v[i].c);
        }
    }

    for (int i = w; i <= wMax; ++i)
        minv = min(minv, cMin[i]);

    cout << minv;

    return 0;
}