#include <iostream>
#include <fstream>

using namespace std;

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

int main()
{
    int nr_gen, pwr, putere, cost, best_putere = 0, best_cost = 30000;

    fin >> nr_gen;
    fin >> pwr;

    int gen[nr_gen][2];

    for(int i = 0; i < nr_gen; i++) {
        fin >> gen[i][0];
        fin >> gen[i][1];
    }

    for(int i = 0; i < nr_gen; i++) {
        putere = 0;
        cost = 0;

        while(putere < pwr) {
            putere += gen[i][0];
            cost += gen[i][1];
        }

        if(cost < best_cost) {
            best_cost = cost;
        }
    }

    fout << best_cost;
}