#include <fstream>
#include <vector>
#include <climits>

using namespace std;

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

vector<int> energie, cost;
vector<vector<int>> dp; // energie, cost
int n, threshold;

int main() {
    cin >> n >> threshold;
    energie.resize(n + 1);
    cost.resize(n + 1);
    int s = 0;
    for (int i = 1 ; i <= n ; ++i) {
        cin >> energie[i] >> cost[i];
        s += energie[i];
    }
    dp.assign(2, vector<int>(s + 1, INT_MAX));
    dp[0][0] = 0;
    int line = 0;
    for (int i = 1 ; i <= n ; ++i) {
        line = 1 - line;
        for (int j = 0 ; j <= s ; ++j) {
            dp[line][j] = dp[1 - line][j];
            if (j >= energie[i] && dp[1 - line][j - energie[i]] != INT_MAX && dp[1 - line][j - energie[i]] + cost[i] < dp[line][j])
                dp[line][j] = dp[1 - line][j - energie[i]] + cost[i];
        }
    }
    int ans = INT_MAX;
    for (int i = threshold ; i <= s ; ++i) {
        ans = min(ans, dp[line][i]);
    }
    cout << ans;
    return 0;
}