#include <iostream>
#include <cstring>
#include <cmath>
#include <cstdio>
#include <queue>
#include <algorithm>
using namespace std;
long long sum[100010];

int main() {
    int T;
    scanf("%d", &T);
    while (T--) {
        int n, k = 0;
        scanf("%d", &n);
        vector<int> v;
        for (int i = 0; i < n; ++i) {
            int x, t;
            scanf("%d%d", &x, &t);
            k += t;
            while (t--) {
                v.push_back(x);
            }
        }
        sort(v.begin(), v.end(), greater<int>());
        sum[0] = v[0];
        for (int i = 1; i < k; ++i) {
            sum[i] = sum[i - 1] + v[i];
        }
        long long ans = 0, cur = 0;
        for (int i = 0; i < k; ++i) {
            cur += sum[i];
            ans = max(ans, cur);
        }
        printf("%I64d\n", ans);
    }
    return 0;
}