#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int N=1e2+3,Inf=1e9+7;
struct node{
    int x,y;
    bool operator <(const node &o)const{
        return (1.0*this->x/this->y)>(1.0*o.x/o.y);
    }
};
node a[N];
/*
    从第k瓶开始喝，喝够m需要的最小代价 
*/
int n,m;
int dfs(int k,int m){
    if(m==0) return 0;
    int ans=(m/a[k].x)*a[k].y;//ans代价 
    if(m%a[k].x==0) return ans;
    return (ans+a[k].y); 
}

int main(){
    int T;
    scanf("%d",&T);
    while(T--){
        scanf("%d %d",&n,&m);
        for(int i=0;i<n;++i)
            scanf("%d %d",&a[i].x,&a[i].y);
        sort(a,a+n);
        int res=Inf;
        for(int i=0;i<n;++i)
            res=min(res,dfs(i,m));
        printf("%d\n",res);
    }
    return 0;
}