#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <string>
#include <map>
#include <vector>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;

int T, n;
struct Point{
    int val, cnt;
}a[55];

bool cmp(Point x, Point y)
{
    return x.val > y.val;
}

int main()
{
    scanf("%d", &T);
    while(T--)
    {
        scanf("%d", &n);
        for(int i = 1; i <= n; i++)
            scanf("%d%d", &a[i].val, &a[i].cnt);
        sort(a + 1, a + n + 1, cmp);
        int ans = 0, res = 0, sum = 0;
        int pos = 1;
        while(pos <= n)
        {
            while(a[pos].cnt != 0)
            {
                res += sum;
                sum += a[pos].val;
                res += a[pos].val;
                ans = max(res, ans);
                a[pos].cnt--;
            }
            if(a[pos].cnt == 0) pos++;
        }
        printf("%d\n", ans);
    }
}