foo.cc: In function 'void firstTree(std::string, std::string)':
foo.cc:13:59: error: expected ';' before 'firstTree'
   13 |         firstTree(s1.substr(0,roots1),s2.substr(0,roots1))//递归左子树
      |                                                           ^
      |                                                           ;
   14 |         firstTree(s1.substr(roots1+1),s2.substr(roots1,len2-roots1+1))
      |         ~~~~~~~~~                                          
foo.cc: In function 'int main()':
foo.cc:20:5: error: 'cim' was not declared in this scope
   20 |     cim>>s1>>s2;
      |     ^~~

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