#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;
typedef long long ll;
const int INF = 0x3f3f3f3f;
const int MAXN = 104;

int x[MAXN], y[MAXN];

int main() {
    int T; scanf("%d", &T);
    while(T--) {
        int n, m;
        scanf("%d%d", &n, &m);
        for(int i = 0; i < n; ++i)
            scanf("%d%d", &x[i], &y[i]);
        int ans = INF;
        for(int i = 0; i < n; ++i) {
            int t = m / x[i];
            if(m % x[i]) ++t;
            ans = min(ans, t * y[i]);
        }
        printf("%d\n", ans);
    }
    return 0;
}