func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long t, n, k;     cin >> t;     while (t--) {       cin >> n;       int arr[n];       int c1 = 0;       for (int i = 0; i < n; i++) {         cin >> arr[i];         if (arr[i] == 1) c1++;       }       if (n - c1 >= c1) {         cout << n - c1 << endl;         for (int i = 0; i < n - c1; i++) {           cout <<  0  ;         }         cout << endl;       } else {         if (c1 % 2 == 0) {           cout << c1 << endl;           for (int i = 0; i < c1; i++) {             cout <<  1  ;           }           cout << endl;         } else {           cout << c1 - 1 << endl;           for (int i = 0; i < c1 - 1; i++) {             cout <<  1  ;           }           cout << endl;         }       }     }   }   