Compilare: user.cpp: In function ‘bool checkAxis(const P&, const P&)’: user.cpp:83:17: warning: unused variable ‘built’ [-Wunused-variable] static bool built = [&]() { ^~~~~ user.cpp: In function ‘int main()’: user.cpp:157:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < lines.size(); ++ i) { ~~^~~~~~~~~~~~~~ user.cpp:114:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dmg.in", "r", stdin); ^ user.cpp:115:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dmg.out", "w", stdout); ^