Problem Statement

You are given an integer sequence $A=(A_1,A_2,\dots,A_N)$ of length $N$. On this sequence, the following operation can be performed:

• Choose $l$ and $r$ $(1\leq l < r \leq N)$ such that $A_l=A_r$, $A_{l+1}=A_{l+2}=\dots=A_{r-1}$, and $A_{l+1}\neq A_l$. Replace each of $A_{l+1},A_{l+2},\dots,A_{r-1}$ with $A_l$. The cost of this operation is $r-l-1$.

You will repeat this operation until there is no $l$ and $r$ $(1\leq l < r \leq N)$ such that $A_l=A_r$, $A_{l+1}=A_{l+2}=\dots=A_{r-1}$, and $A_{l+1}\neq A_l$. Find the minimum total cost of such a series of operations.

Constraints

• $3 \leq N \leq 5 \times 10^5$
• $1 \leq A_i \leq N$
• All input values are integers.

Input

The input is given from Standard Input in the following format:

N
A_1 A_2 \dots A_N

Output

Print the answer.