#include <bits/stdc++.h>
#define nmax 22242423
using namespace std;


int n, k;

int v[5001];
int main()
{
    freopen("energii.in", "r", stdin);
    freopen("energii.out", "w", stdout);
int c, e;
    cin >> n;
    cin >> k;

    for(int i = 1; i <= k; i++)
        v[i] = nmax;

    for(int i = 1; i <= n; i++)
    {
        cin >> c >> e;

        for(int j = k; j >= 1; j--)
        {
            if(j >= c)
            {
                v[j] = min(v[j-c] + e,v[j]);
            }

        }

    }

cout << v[k];


    return 0;
}