#include <fstream>
#include <iostream>
#define INF 0x3f3f3f3f
using namespace std;

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

int n, w, e[1005], v[1005], cmin[5005];

inline int min(int a, int b)
{
    return a < b ? a : b;
}

int main()
{
    f >> n >> w;
    for(int i = 1; i <= n; ++i)
        f >> e[i] >> v[i];
    //cmin[0] = INF;
    for(int i = 1; i <= w; ++i)
    {

        cmin[i] = INF;
        for(int j = 1; j <= n; ++j)
        {
            if(i >= e[j])
                cmin[i] = min(cmin[i], cmin[i - e[j]] + v[j]);
        }
    }
    fout << cmin[w] << '\n';
}