Compilare: user.cpp: In function ‘void valid(int, int&)’: user.cpp:16: warning: unused variable ‘i’ user.cpp: In function ‘int main()’: user.cpp:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result