#include <bits/stdc++.h>
using namespace std;
void DAU(const string& task = "") {
    if (!task.empty())
        freopen((task + ".in").c_str(), "r", stdin),
        freopen((task + ".out").c_str(), "w", stdout);
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
}
void PLEC() {
    exit(0);
}
const int GMAX(15051), INF(1e9);
int dp[GMAX], n, g, e, c, res(INF);
signed main() {
    DAU("energii");
    fill(dp + 1, dp + GMAX, INF);
    cin >> n >> g;
    while (n--) {
        cin >> e >> c;
        for (int i = g; i >= 0; --i)
            dp[i + e] = min(dp[i] + c, dp[i + e]);
    }
    for (int i = g; i < GMAX; ++i)
        res = min(res, dp[i]);
    if (res == INF)
        res = -1;
    cout << res;
    PLEC();
}