#include <iostream>
#include <string>
#include <cstring>
int KASE, x[110], y[110];
int f[2000010];
int Min(int x, int y)
{
    return x > y ? y : x;
}
int Max(int x, int y)
{
    return x > y ? x : y;
}
const int Inf = 0x3f3f3f3f;

int main()
{
    std::cin >> KASE;
    for (int Kase = 1; Kase <= KASE; Kase++)
    {
        int n, m;
        std::cin >> n >> m;
        for (int i = 1; i <= n; i++)
            std::cin >> x[i] >> y[i];
        int Ans = Inf;
        for (int i = 1; i <= n; i++)
        {
            if (m % x[i] == 0)
                Ans = Min(Ans, (m / x[i]) * y[i]);
            else
                Ans = Min(Ans, (m / x[i] + 1) * y[i]);
        }
        std::cout << Ans << std::endl;
    }
    return 0;
}