#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("fast-math")
#include <bits/stdc++.h>
using namespace std;
int n, rucsac, dp[5005], s;
struct ruc
{
    int cant, cost;
} v[1005];
ifstream fin("energii.in");
ofstream fout("energii.out");
int32_t main(int argc, char * argv[])
{
    fin >> n;
    fin >> rucsac;
   for(int i = 1; i <= rucsac; ++i)
   {
       dp[i] = 1000000000;
   }
    for(int i = 1; i <= n; ++i)
    {
        fin >> v[i].cant >> v[i].cost;
    }
    for(int i = 1; i <= n; ++i)
    {
        for(int j = rucsac; j >= 0; --j)
        {
            if(dp[j] != 1000000000)
            {
                dp[min(j + v[i].cant, rucsac)] = min(dp[min(j + v[i].cant, rucsac)], dp[j] + v[i].cost);
            }
        }
    }
    fout << dp[rucsac];
    return 0;
}