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

const int MAX_N(26),INF(100);

typedef long long ll;

int n,ch[MAX_N*INF],num;

#define rep(i,b,n) for(int i(b);i<n;++i)

int main()
{
    void solve();
    //输入
    int T;
    cin>>T;
    while(T--)
    {
        cin>>n;
        int val,cnt;
        num=0;
        rep(i,0,n)
        {
            cin>>val>>cnt;
            rep(j,num,num+cnt)ch[j]=val;
            num+=cnt;
        }
        solve();
    }
    return 0;
}

void solve()
{
    sort(ch,ch+num);

    ll val,ans(0);
    rep(i,0,num)
    {
        val=0;
        rep(j,i,num)val+=ll(j-i+1)*ch[j];
        ans=max(ans,val);
        if(ch[i]>=0)break;
    }
    cout<<ans<<endl;
}