#include <bits/stdc++.h>

#define ll long long
#define el endl
#define umi unordered_map<int, int>
#define umll unordered_map<ll, ll>
#define all(vect) vect.begin(), vect.end()
#define reset(A) memset(A, 0, sizeof(A))
#define approx(n) fixed << setprecision(n)
#define pb push_back

const int mod = 1e9 + 7;

using namespace std;

void solve()
{
    int n, sum = 0;
    cin >> n;
    int a[n];
    for(int i =0; i< n; i++)
    {
        cin >>a[i];
        sum += a[i];
    }
    sort(a, a + n, greater<int>());
    if(!(sum % 3))
    {
        for(int i = 0; i< n; i++)
            cout << a[i];
        cout << el;
        return;
    }
    else if(sum % 3 == 1)
    {
        int ex = -1;
        for(int i = n - 1; i >= 0; i--)
        {
            if(a[i] % 3 == 1)
            {
                ex = i;
                break;
            }
        }
        if(ex > -1)
        {
            for(int i = 0; i < n; i++)
            {
                if(i != ex)
                    cout << a[i];
            }
            cout << el;
            return;
        }
    }
    else if(sum % 3 == 2)
    {
        int ex1 = -1, ex2 = -1, ex = -1;
        for(int i = n - 1; i >= 0; i--)
        {
            if(a[i] % 3 == 2)
            {
                ex = i;
                break;
            }
        }
        if(ex > -1)
        {
            for(int i = 0; i < n; i++)
            {
                if(i != ex)
                    cout << a[i];
            }
            cout << el;
            return;
        }
        for(int i = n - 1; i >= 0; i--)
        {
            if(a[i] % 3 == 1)
            {
                ex1 = i;
                break;
            }
        }
        for(int i = ex1 - 1; i >= 0; i--)
        {
            if(a[i] % 3 == 1)
            {
                ex2 = i;
                break;
            }
        }
        if(ex1 > -1 && ex2 > -1)
        {
            for(int i = 0; i < n; i++)
            {
                if(i != ex1 && i != ex2)
                    cout << a[i];
            }
            cout << el;
            return;
        }
    }
    cout << -1 << el;
}

int main()
{
    int t = 1;
    cin >> t;
//  cin.ignore();
    while(t--)
    {
        solve();
    }
    return 0;
}