#include <bits/stdc++.h>  

using namespace std; 

const int max_size = 6e3 + 20, INF = 1e9 + 7, rmax = 15;

int dp[max_size];

void solve()
{
    int n, g;
    cin >> n >> g;
    for (int i = 1; i < max_size; i++)
    {
        dp[i] = INF;
    }
    dp[0] = 0;
    for (int i = 1; i <= n; i++)
    {
        int w, x;
        cin >> w >> x;
        for (int j = max_size; j >= w; j--)
        {
            dp[j] = min(dp[j], dp[j - w] + x);
        }
    }
    int ans = dp[g];
    for (int i = g + 1; i < max_size; i++)
    {
        ans = min(ans, dp[i]);
    }
    if (ans == INF)
    {
        ans = -1;
    }
    cout << ans << "\n";
}

signed main() 
{ 
#ifdef LOCAL 
    freopen("test.in", "r", stdin); 
    freopen("test.out", "w", stdout);
#else
    freopen("energii.in", "r", stdin);
    freopen("energii.out", "w", stdout);
#endif // LOCAL 
    ios_base::sync_with_stdio(false); 
    cin.tie(0); 
    cout.tie(0); 
    long long tt;
    tt = 1;
    while (tt--)
    {
        solve();
    }
    return 0; 
}