#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
    int t;
    scanf("%d",&t);
    vector<int> a;
    while(t--){
        a.clear();
        int n;
        scanf("%d",&n);
        while(n--){
            int val,cnt;
            scanf("%d%d",&val,&cnt);
            while(cnt--){
                a.push_back(val);
            }
        }
        sort(a.begin(),a.end(),greater<int>());
        int ans=0;
        int temp=0;
        int cur=0;

        for(int i=0;i<a.size();i++){
            temp = temp+cur+a[i];
            ans = max(ans,temp);
            cur+=a[i];
        }
        printf("%d\n",ans);
    }
    return 0;
}