Compilare: user.cpp: In function ‘void df(int)’: user.cpp:34: warning: comparison between signed and unsigned integer expressions user.cpp:48: warning: comparison between signed and unsigned integer expressions user.cpp:57: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:75: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:76: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:78: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:80: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:92: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:95: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result