Eroare de compilare: user.cpp: In function ‘void back(int, int)’: user.cpp:11: error: ‘ok’ was not declared in this scope user.cpp: In function ‘int main()’: user.cpp:38: error: ‘i’ was not declared in this scope user.cpp:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result