#include <bits/stdc++.h>
#define int long long
#define cin ci
#define cout co
using namespace std;
ifstream cin("energii.in");
ofstream cout("energii.out");
const int inf = 1e9;
int n ,k;
vector<pair<int , int>> v;
vector<int> dp;
int32_t main()
{
    cin >> n >> k;
    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;
    dp.assign(sum + 5, inf);
    dp[0] = 0;
    for(int i = 1; i <= n; i ++)
        for(int j = sum; j >= v[i].first; j --)
            if(dp[j - v[i].first] != inf)
                dp[j] = min(dp[j], dp[j - v[i].first] + v[i].second);

    int ans = inf;
    for(int i = k; i <= sum; i ++)
        ans = min(ans, dp[i]);
    cout << ans;
    return 0;
}