#include<fstream>
#define nMax 1001
#define eMax 5001
using namespace std;
int N, eNecesar, C[nMax], E[nMax], dp[nMax][eMax];

ifstream f("energii.in");
ofstream g("energii.out");

int main()
{
    f >> N >> eNecesar;
    for(int i = 1; i <= N; i++)
        f >> E[i] >> C[i];
    for(int i = 1; i <= N; i++){
        for(int j = 0; j <= eNecesar; j++)
    {
        if(E[i] > eNecesar) E[i] = eNecesar;


        if(E[i] > j)dp[i][j] = dp[i-1][j];
        else
            if( dp[i][j] != 0) dp[i][j] = min(dp[i][j], dp[i-1][j-E[i]] + C[i]);
        else dp[i][j] = dp[i-1][j-E[i]] + C[i];
        //g << dp[i][j] << " ";
    }
     //g << '\n';
    }
    g << dp[N][eNecesar];

    return 0;
}