#pragma GCC optimize("-Ofast","-funroll-all-loops")
#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=110;
int dp[N*N*2],x[N],y[N],n,res,m;
inline  void solve(){
    cin>>n>>m; res=1e9; 
    for(int i=1;i<=n;i++)    cin>>x[i]>>y[i],res=min(res,(m+x[i]-1)/x[i]*y[i]);
    cout<<res<<endl;
}
signed main(){
    int T; cin>>T; while(T--) solve();
    return 0;
}