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

ifstream is("energii.in");
ofstream os("energii.out");

int n, S, x, y, maxim = -INF, minim = INF;
vector<int> a;

int main()
{
    is >> n >> S;
    a.resize(2 * S + 1, INF);
    a[0] = 0;
    for ( int i = 1 ; i <= n; i++ )
    {
        is >> x >> y;
        maxim = max( maxim, x );
        for ( int j = x; j <= 2 * S; j += x )
            a[j] = min( a[j-x] + y, a[j] );
    }
    for ( int i = S; i <= 2 * S; i++ )
        minim = min( minim, a[i] );
    os << minim;
    return 0;
}