Compilare: user.cpp: In function ‘void df(int)’: user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void df2(int)’: user.cpp:110: warning: comparison between signed and unsigned integer expressions user.cpp:123: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:131: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:132: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:134: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:137: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:148: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result