Compilare: main.cpp: In function 'void DFS2(int, int, long long int, long long int)': main.cpp:103:19: warning: variable 'son2' set but not used [-Wunused-but-set-variable] int son1 = 0, son2 = 0; ^~~~ main.cpp: In constructor 'InputReader::InputReader(const char*)': main.cpp:25:43: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buffer, SIZE, 1, input_file); ^ main.cpp: In member function 'void InputReader::advance()': main.cpp:70:47: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buffer, SIZE, 1, input_file); ^