func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 110000;   string s;   int n, cnt1, cnt0, cntq, m, p;   char last0, last1;   int may01, may10;   int main() {     cin >> s;     n = s.size();     for (int i = 0; i < n; i++)       if (s[i] ==  1 )         cnt1++;       else if (s[i] ==  0 )         cnt0++;       else         cntq++;     m = n / 2 + n % 2 - 1;     p = n - m - 2;     if (cnt1 <= m) puts( 00 );     if (m + 1 - cnt1 <= cntq && m + 1 >= cnt1) {       int q1 = (m + 1 - cnt1);       int q0 = cntq - q1;       if (q0 + cnt0 == p + 1) {         if (s[n - 1] ==  1  || (s[n - 1] ==  ?  && q1 > 0)) {           may01 = 1;         }         if (s[n - 1] ==  0  || (s[n - 1] ==  ?  && q0 > 0)) {           may10 = 1;         }         if (may01) puts( 01 );         if (may10) puts( 10 );       }     }     if (cnt0 <= p) puts( 11 );   }   