#include<iostream>
#include<cstdio>
#include<cstring>
#include<cctype>
#include<algorithm>
#include<queue>
#include<cmath>
#include<set>
#include<vector>
#define debug(x) cerr << #x << "=" << x << endl
#define LL long long 
#define MAXN 1000010
using namespace std;
int read(){
    int x = 0, f = 1;
    char ch = getchar();
    for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -1;
    for(; isdigit(ch); ch = getchar()) x = x * 10 + ch - '0';
    return x * f;
}

const int inf = 1e7;
int T, n;
struct Note{int v, c;
} a[30];
int b[MAXN];

int main(){
    T = read();
    while(T--){
        n = read();
        for(int i = 1; i <= n; i++) a[i].v = read(), a[i].c = read();
        int cnt = 0;
        for(int i = 1; i <= n; i++)
        for(int j = 1; j <= a[i].c; j++) b[++cnt] = a[i].v;
        sort(b + 1, b + cnt + 1);
        int t = 1;
        while(b[t] < 0) t++;
        int sum = 0, ans = -inf, now = 0;
        for(int i = t; i <= cnt; i++)
        now += b[i] * (i - t + 1), sum += b[i]; ans = max(ans, now);
        for(int i = t - 1; i; i--) now = now + sum + b[i], sum += b[i], ans = max(now, ans);
        printf("%d\n", ans);
    }
    return 0;
}