#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <vector>
using namespace std;
typedef long long ll;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<int, int> PII;
typedef vector<int> VI;
#define fi first
#define se second
#define MP make_pair

int read()
{
    int v = 0, f = 1;
    char c = getchar();
    while (c < 48 || 57 < c) {if (c == '-') f = -1; c = getchar();}
    while (48 <= c && c <= 57) v = (v << 3) + v + v + c - 48, c = getchar();
    return v * f;
}

const int INF = 1e9;

int main()
{
    int cas = read();
    while (cas--)
    {
        int n = read(), m = read();
        int ans = INF;
        for (int i = 1; i <= n; i++)
        {
            int x = read(), y = read();
            int t = m / x;
            if (m % x > 0)
                t++;
            ans = min(ans, t * y);
        }
        printf("%d\n", ans);
    }
}