Compilare: user.cpp: In function ‘void init()’: user.cpp:26: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:27: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp: In function ‘int read_long()’: user.cpp:35: warning: array subscript has type ‘char’ user.cpp: In function ‘int main(int, const char**)’: user.cpp:90: warning: comparison between signed and unsigned integer expressions