///dp[i]-costul minim pt energia i?

#include <fstream>

using namespace std;

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

const int INF = 1e9;
const int N = 5000;
int dp[N + 1];

struct clasa
{
    int e, cost;
} a[N + 1];

int n, energ, mx;

int main()
{
    cin >> n >> energ;
    for (int i = 1; i <= n; ++i)
        cin >> a[i].e >> a[i].cost, mx = max (mx, a[i].cost);
    for (int i = 0; i <= mx; ++i)
        dp[i] = INF;
    dp[0] = 0;
    for (int i = 0; i <= mx; ++i)
    {
        for (int j = 1; j <= n; ++j)
            if (a[j].e <= i)
                dp[i] = min (dp[i], dp[i - a[j].e] + a[j].cost);
    }
    cout << dp[energ] << "\n";
    return 0;
}