#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
#define ll __int64
struct node
{
    ll val,y;
}a[5000];
ll b[5000];
int cmp(node a,node b)
{
    return a.val<b.val;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        ll output=0;
        int n;
        scanf("%d",&n);
        for(int i=0;i<n;i++)
        {
            ll x,y;
            scanf("%I64d%I64d",&a[i].val,&a[i].y);
        }
        int cont=0;
        sort(a,a+n,cmp);
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<a[i].y;j++)
            {
                b[cont++]=a[i].val;
            }
        }
        for(int i=0;i<cont;i++)
        {
            ll sum=0;
            ll tmp=1;
            for(int j=i;j<cont;j++)
            {
                sum+=tmp*b[j];
                tmp++;
            }
            output=max(output,sum);
        }
        printf("%I64d\n",output);
    }
}