Compilare: user.cpp: In constructor ‘Permut::Permut(int)’: user.cpp:74:8: warning: ‘Permut::N’ will be initialized after [-Wreorder] int N, level; ^ user.cpp:73:13: warning: ‘std::vector<int> Permut::Stack’ [-Wreorder] vector<int> Stack; ^ user.cpp:12:8: warning: when initialized here [-Wreorder] Permut(int n): N(n), Stack(n+1){} ^ user.cpp: In member function ‘void Permut::back(int)’: user.cpp:57:12: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(valid(level)) ^ user.cpp: In function ‘int main()’: user.cpp:83:28: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(FOUT, "w", stdout); ^