foo.cpp:1:1: error: 'include' does not name a type
 include <bits/stdc++.h>
 ^~~~~~~
foo.cpp: In function 'void dfs(int, int, int, int)':
foo.cpp:9:22: error: 'printf' was not declared in this scope
 printf("%c", after[q]);
                      ^
foo.cpp: In function 'int main()':
foo.cpp:16:33: error: 'scanf' was not declared in this scope
 scanf("%s%s", mid + 1, after + 1);
                                 ^
foo.cpp:17:19: error: 'strlen' was not declared in this scope
 n = strlen(mid + 1);
                   ^