#include <bits/stdc++.h>
using namespace std;

int n, w, dp[1010][5010], s[1010], ans = 1e9;
pair <int,int> a[1010];
#define x first
#define y second

int main(){
    ifstream cin ("energii.in");
    ofstream cout ("energii.out");
    cin >> n >> w;
    for (int i=1; i<=n; i++) cin >> a[i].x >> a[i].y, s[i] = s[i-1] + a[i].x;
    for (int i=1; i<=n; i++){
        for (int j=1; j<=w; j++) dp[i][j] = 1e9;
    }
    for (int i=1; i<=n; i++){
        for (int j=0; j<=s[i-1]; j++){
            if (j + a[i].x >= w) ans = min(ans, dp[i][j] + a[i].y);
            else dp[i][j + a[i].x] = min(dp[i][j + a[i].x], dp[i][j] + a[i].y);
        }
    }
    cout << ans;
    return 0;
}