Codeforces-560D Almost All Divisors

#include <bits/stdc++.h>
using namespace std;
int main()
{
    long long int n,i,j,k,l,c,d,f,t,x;
    cin>>t;
    while(t--)
    {
        cin>>n;
        vector<long long int> a(n);
        for(i=0;i<n;i++)
        cin>>a[i];
        
        vector<long long int> v;
        sort(a.begin(),a.end());
        
        x=a[0]*a[n-1];
        c=0;
        for(i=2;i*i<=x;i++)
        {
            if(x%i==0)
            {
                v.push_back(i);
                if(i!=(x/i))
                v.push_back(x/i);
            }
        }
        sort(v.begin(),v.end());
        
        
        if(v==a)
        cout<<x<<endl;
        else
        cout<<"-1"<<endl;
    }
	return 0;
}