func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string s;     cin >> s;     int a = (s.size() + 1) / 2 - 1;     int b = s.size() / 2 - 1;     bool f00 = false, f01 = false, f10 = false, f11 = false;     int cq = 0, c0 = 0, c1 = 0;     for (int i = 0; i < s.size(); i++) {       if (s[i] ==  0 )         c0++;       else if (s[i] ==  1 )         c1++;       else         cq++;     }     if (cq + c1 >= a + 2) f11 = true;     if (c1 <= a) f00 = true;     if (c1 <= a + 1 and c1 + cq >= a + 1) {       int q1 = (a + 1) - c1;       int q0 = cq - q1;       if (s.back() ==  ? ) {         if (q1) f01 = true;         if (q0) f10 = true;       } else if (s.back() ==  0 )         f10 = true;       else         f01 = true;     }     if (f00) printf( 00 n );     if (f01) printf( 01 n );     if (f10) printf( 10 n );     if (f11) printf( 11 n );     return 0;   }   