#include <bits/stdc++.h>
using namespace std;

#define N 26010

int t, n, m, val, cnt, a[N], s[N];

int main() {
//    freopen("a.in", "r", stdin);
    scanf("%d", &t);
    while (t --) {
        scanf("%d", &n);
        m = 0;
        for (int i = 1; i <= n; i ++) {
            scanf("%d %d", &val, &cnt);
            for (int j = 0; j < cnt; j ++) a[++m] = val;
        }
        if (!m) {
            puts("0"); continue;
        }
        sort(a + 1, a + m + 1);
        s[m+1] = 0;
        for (int i = m; i >= 1; i --) s[i] = s[i+1] + a[i];
        int ans = 0;
        for (int i = m; i >= 1 && s[i] > 0; i --) ans += s[i];
        printf("%d\n", ans);
    }
    return 0;
}