func_code_string: #include <bits/stdc++.h>   using namespace std;   int t, n, m;   long long a, k, ak;   char c;   unordered_map<long long, bool> ma;   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     cin >> t;     for (int ti = 1; ti <= t; ++ti) {       ma.clear();       cin >> n >> m;       k = (1ll << m) - n;       for (int i = 1; i <= n; ++i) {         a = 0;         for (int j = m - 1; j >= 0; --j) {           cin >> c;           a |= (c ==  1  ? (1ll << j) : 0ll);         }         ma[a] = 1;       }       a = (k - 1) / 2;       ak = k = a + 1;       for (pair<long long, bool> tw : ma) {         if (tw.first <= a) --ak;       }       while (ak < k) {         if (!ma[++a]) ++ak;       }       for (int i = m - 1; i >= 0; --i) {         cout << (a & (1ll << i) ? 1 : 0);       }       cout <<   n ;     }     return 0;   }   