Compilare: user.cpp: In function ‘int main()’: user.cpp:61: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:61: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:62: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:64: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:66: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:71: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void df(int)’: user.cpp:11: warning: ‘j’ may be used uninitialized in this function