1001 Drink
/*
* problem:Drink
* method:暴力
* date:2020/07/19
*/
#include<iostream>
#define ll long long
using namespace std;
const int maxn=105;
int t,n,m;
int x,y;
int main(){
int i,j;
cin>>t;
while(t--){
cin>>n>>m;
int min=1000000,a,b;
for(i=0;i<n;i++){
cin>>x>>y;
a=m/x;
if(a*x!=m) a++;
b=a*y;
min=min<b?min:b;
}
cout<<min<<endl;
}
return 0;
}