#include<iostream>
#include<cmath>

using namespace std;

int x[100],y[100],ping[100];

int main()
{
    int n,m,mi=10000;
    int k,i;
    int test;
    cin>>test;
    while((test--)!=0)
    {
        cin>>n>>m;
        for(i=0;i<n;i++)
        {
            cin>>x[i]>>y[i];
            ping[i]=m/x[i];
            if(m!=ping[i]*x[i])
                ping[i]++;
            mi=min(mi,ping[i]*y[i]);
        }
        cout<<mi<<endl;
        mi=10000;
    }
    return 0;
}