Eroare de compilare: user.cpp: In function ‘void back(int)’: user.cpp:10: error: ‘ok’ was not declared in this scope user.cpp:12: error: ‘V’ was not declared in this scope user.cpp:17: error: ‘X’ was not declared in this scope user.cpp:24: error: ‘E’ was not declared in this scope user.cpp:25: error: ‘V’ was not declared in this scope user.cpp:27: error: ‘E’ was not declared in this scope user.cpp:28: error: ‘V’ was not declared in this scope user.cpp: In function ‘int main()’: user.cpp:37: error: ‘n’ was not declared in this scope user.cpp:38: error: ‘E’ was not declared in this scope user.cpp:41: error: ‘x’ was not declared in this scope