Palindrome Check

A $1$-indexed array $P$ of length $M$ is called a *palindrome* if $P_i = P_{M+1-i}$ holds for each $1 \le i \le M$. For example, $[2, 2], [3, 1, 3], [4], [12, 12]$ are palindromes whereas $[1, 1, 2]$ and $[12, 21]$ are not. Chef loves palindromes. Chef also loves the number $K$. Chef has with him an array $A$ of length $N$. He can repeatedly modify the array as follows: - Insert an occurre