#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 105;
int x[N], y[N];
int main() {
    int T, n, m;
    scanf("%d", &T);
    while(T--) {
        scanf("%d%d", &n, &m);
        for(int i = 0; i < n; i++) {
            scanf("%d%d", &x[i], &y[i]);
        }
        int ans = 1e9;
        for(int i = 0; i < n; i++) {
            ans = min(ans, (m + x[i] - 1) / x[i] * y[i]);
        }
        printf("%d\n", ans);
    }
    return 0;
}