Compilare: user.cpp: In function ‘int df1(int)’: user.cpp:25: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int df2(int)’: user.cpp:54: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:76: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:77: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:79: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:81: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:85: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result