#include <bits/stdc++.h>
#define cin ci
#define cout co
using namespace std;
ifstream cin("energii.in");
ofstream cout("energii.out");
const int inf = 1e9;
const int Wmax = 5e3 + 5;
int n, g;
vector<pair<int, int>> v;
int main()
{
    cin >> n >> g;
    v.resize(n + 5);
    int sum = 0;
    for(int i = 1; i <= n; i++)
    {
       cin >> v[i].first >> v[i].second;
       sum += v[i].first;
    }

    vector<int> dp(Wmax + 5, inf);
    dp[0] = 0;
    for(int i = 1; i <= n; i++)
        for(int j = Wmax; j >= v[i].first; j --)
            dp[j] = min(dp[j], dp[j - v[i].first] + v[i].second);

    int ans = inf;
    for(int i = g; i <= Wmax; i++)
        ans = min(ans, dp[i]);
    cout << (ans != inf ? ans : -1);
    return 0;
}