#include<bits/stdc++.h>
#define D(...) fprintf(stderr,__VA_ARGS__)
#define int long long
#define LL long long
#define MP make_pair
#define PB push_back
#define fi first
#define se second
#define ALL(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>=(b);--i)
using namespace std;
typedef pair<int,int>PII;typedef vector<int>VI;typedef vector<PII>VII;
template<typename T>void rd(T&x){int f=0,c;while(!isdigit(c=getchar()))f^=!(c^45);x=(c&15);while(isdigit(c=getchar()))x=x*10+(c&15);if(f)x=-x;}
template<typename T>void pt(T x,int c=-1){if(x<0)putchar('-'),x=-x;if(x>9)pt(x/10);putchar(x%10+48);if(c!=-1)putchar(c);}
const int N=105;
int T,n,m,x[N],y[N],f[100005];
void umin(int&x,int y){
    if(y<x)x=y;
}
signed main(){
    rd(T);
    while(T--){
        rd(n),rd(m);
        rep(i,1,n)rd(x[i]),rd(y[i]);
        int ans=0X3F3F3F3F3F3F3F3FLL;
        rep(i,1,n){
            ans=min(ans,(m+x[i]-1)/x[i]*y[i]);
        }
        pt(ans,'\n');
    }
    return 0;
}