Minimize Distinct

You are given an array $A$ of length $N$, such that $1 \le A_i \le N$ for each $1 \le i \le N$. For the each pair $(L, R)$ such that $1 \le L \le R \le N$, we define the array $f(L, R)$ as follows: - Consider an array $B$ of length $N$. - For each index $i$ ($1 \le i \le N$), - If $L \le A_i \le R$, set $B_i$ to be $A_i + 1$. - Otherwise, set $B_i$ to be $A_i - 1$. - We define $f(L, R) =