Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

В условии задачи недавно были сделаны правки. Просмотреть изменения.

×
D. Flood Fill

time limit per test

2 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputYou are given a line of $$$n$$$ colored squares in a row, numbered from $$$1$$$ to $$$n$$$ from left to right. The $$$i$$$-th square initially has the color $$$c_i$$$.

Let's say, that two squares $$$i$$$ and $$$j$$$ belong to the same connected component if $$$c_i = c_j$$$, and $$$c_i = c_k$$$ for all $$$k$$$ satisfying $$$i < k < j$$$. In other words, all squares on the segment from $$$i$$$ to $$$j$$$ should have the same color.

For example, the line $$$[3, 3, 3]$$$ has $$$1$$$ connected component, while the line $$$[5, 2, 4, 4]$$$ has $$$3$$$ connected components.

The game "flood fill" is played on the given line as follows:

- At the start of the game you pick any starting square (this is not counted as a turn).
- Then, in each game turn, change the color of the connected component containing the starting square to any other color.

Find the minimum number of turns needed for the entire line to be changed into a single color.

Input

The first line contains a single integer $$$n$$$ ($$$1 \le n \le 5000$$$) — the number of squares.

The second line contains integers $$$c_1, c_2, \ldots, c_n$$$ ($$$1 \le c_i \le 5000$$$) — the initial colors of the squares.

Output

Print a single integer — the minimum number of the turns needed.

Examples

Input

4 5 2 2 1

Output

2

Input

8 4 5 2 2 1 3 5 5

Output

4

Input

1 4

Output

0

Note

In the first example, a possible way to achieve an optimal answer is to pick square with index $$$2$$$ as the starting square and then play as follows:

- $$$[5, 2, 2, 1]$$$
- $$$[5, 5, 5, 1]$$$
- $$$[1, 1, 1, 1]$$$

In the second example, a possible way to achieve an optimal answer is to pick square with index $$$5$$$ as the starting square and then perform recoloring into colors $$$2, 3, 5, 4$$$ in that order.

In the third example, the line already consists of one color only.

Codeforces (c) Copyright 2010-2020 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Sep/25/2020 00:19:15 (f3).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|