#include <bits/stdc++.h>

std::ifstream in("energii.in");
std::ofstream out("energii.out");

#define mx 100001
int G,W,E[mx],C[mx],Dp[mx];

int main(){
    in>>G>>W;
    for(int i=1; i<=G; ++i) in>>E[i]>>C[i];
    for(int i=1; i<mx; ++i) Dp[i] = (1<<25);

    for(int i=1; i<=G; ++i)
        for(int j=W-E[i]; j>=0; --j)
            Dp[j+E[i]] = std::min(Dp[j+E[i]], Dp[j] + C[i]);

    out<<Dp[W];

    return 0;
}