#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <algorithm>
#define ll long long
#define mst(a,x) memset(a,x,sizeof(a))
#define For(i, t) for(int i = 0; i < t; i++)
#define Debug(x) cerr << #x << " = "  << x << endl;
using namespace std;

const int N = 35;
pair <int, int> a[N];
int main() {
    int T;

    scanf("%d", &T);
    while(T--) {
        int n;
        scanf("%d", &n);
        For(i, n) scanf("%d%d", &a[i].first, &a[i].second);
        sort(a, a + n);
        reverse(a, a + n);
        int ans = 0, sum = 0;
        For(i, n) {
            while(a[i].second--) {
                if(sum + a[i].first <= 0) break;
                ans += sum + a[i].first;
                sum += a[i].first;
            }
        }
        printf("%d\n", ans);
    }
    return 0;
}