Compilare: user.cpp: In function ‘void dfs(int, std::vector<int, std::allocator<int> >*, bool*)’: user.cpp:19: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void ctc()’: user.cpp:47: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:54: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:55: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:56: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:59: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result