Compilare: user.cpp: In function ‘int main()’: user.cpp:25:15: warning: suggest parentheses around comparison in operand of ‘&’ [-Wparentheses] if (n & 1 == 0 or (n & 1) and p[(n-1) / 2] == 0) out << 2 << " " << 1 + n << '\n'; ^ user.cpp:25:35: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if (n & 1 == 0 or (n & 1) and p[(n-1) / 2] == 0) out << 2 << " " << 1 + n << '\n'; ^