Compilare: user.cpp: In function ‘void phi()’: user.cpp:13: warning: operation on ‘i’ may be undefined user.cpp:15: warning: operation on ‘i’ may be undefined user.cpp: In function ‘int main()’: user.cpp:63: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:64: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:65: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result