Compilare: main.cpp: In function 'int main()': main.cpp:4:50: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] #define FL(nm) do { freopen(nm ".in", "r", stdin); freopen(nm ".out", "w", stdout); } while (false) ^ main.cpp:6:5: note: in expansion of macro 'FL' FL("diagonale"); ^~ main.cpp:4:83: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] #define FL(nm) do { freopen(nm ".in", "r", stdin); freopen(nm ".out", "w", stdout); } while (false) ^ main.cpp:6:5: note: in expansion of macro 'FL' FL("diagonale"); ^~ main.cpp:9:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ main.cpp:11:57: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] for (auto& _v : v) for (int& i : _v) scanf("%d", &i); ^