Compilare: user.cpp: In member function ‘bool ev::operator<(const ev&) const’: user.cpp:18: warning: suggest parentheses around ‘&&’ within ‘||’ user.cpp: In function ‘void add(int, int)’: user.cpp:39: warning: suggest parentheses around arithmetic in operand of ‘^’ user.cpp: In function ‘int query(int)’: user.cpp:45: warning: suggest parentheses around arithmetic in operand of ‘^’ user.cpp: In function ‘int main()’: user.cpp:75: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result