func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T>   bool ckmin(T& a, const T& b) {     return b < a ? a = b, 1 : 0;   }   template <class T>   bool ckmax(T& a, const T& b) {     return a < b ? a = b, 1 : 0;   }   mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());   const long double pii = 3.14159265359;   const int MOD = 1000000007;   const char nl =   n ;   const int MX = 200001;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     int T;     cin >> T;     while (T-- != 0) {       int N;       cin >> N;       vector<int> v(2);       for (int x = 0; x < (N); x++) {         int nb;         cin >> nb;         v[nb]++;       }       if (v[0] >= v[1]) {         cout << v[0] << nl;         for (int x = 0; x < (v[0]); x++) cout << 0 <<    ;       } else {         cout << v[1] - v[1] % 2 << nl;         for (int x = 0; x < (v[1] - v[1] % 2); x++) {           cout << 1 <<    ;         }       }       cout << nl;     }     return 0;   }   