#include <bits/stdc++.h>   using namespace std;   int main() {     int n, t, cont[8] = {0}, i;     cin >> n;     for (int i = 0; i < n && cin >> t; i++) cont[t]++;     if (cont[1] != n / 3 || cont[5] + cont[7] || cont[4] > cont[2] ||         cont[3] > cont[6] || cont[2] + cont[3] != cont[4] + cont[6])       cout << -1;     else {       for (i = 0; i < cont[3]; i++) cout << 1 <<     << 3 <<     << 6 << endl;       for (i = 0; i < cont[4]; i++) cout << 1 <<     << 2 <<     << 4 << endl;       for (i = 0; i < cont[2] - cont[4]; i++)         cout << 1 <<     << 2 <<     << 6 << endl;     }     return 0;   }   