Squirrel Liss loves nuts. There are *n* trees (numbered 1 to *n* from west to east) along a street and there is a delicious nut on the top of each tree. The height of the tree *i* is *h*<sub class="lower-index">*i*</sub>. Liss wants to eat all nuts.

Now Liss is on the root of the tree with the number 1. In one second Liss can perform one of the following actions:
 -  Walk up or down one unit on a tree. -  Eat a nut on the top of the current tree. -  Jump to the next tree. In this action the height of Liss doesn't change. More formally, when Liss is at height *h* of the tree *i* (1 ≤ *i* ≤ *n* - 1), she jumps to height *h* of the tree *i* + 1. This action can't be performed if *h* &gt; *h*<sub class="lower-index">*i* + 1</sub>. 
Compute the minimal time (in seconds) required to eat all nuts.
The first line contains an integer *n* (1  ≤  *n* ≤ 10<sup class="upper-index">5</sup>) — the number of trees.

Next *n* lines contains the height of trees: *i*-th line contains an integer *h*<sub class="lower-index">*i*</sub> (1 ≤ *h*<sub class="lower-index">*i*</sub> ≤ 10<sup class="upper-index">4</sup>) — the height of the tree with the number *i*.

def calculateTime(Height, totalTrees):
	#squirrel going to spend 1 unit of time at each tree eating fruit
	#Squirrel going to spend 1 unit of time at each tree for jumping to next Tree [except at last Tree, no jump is required]
	#For reach tree, squirral is  either moving up/down to reach top of tree..
	#if previous tree is bigger than next..then squirrel have to move down.. else moveUpFromThatHeight
	#totalTime= eatingTimeAtEachTree*totalTrees + jumpingTONextTree*(totalTrees-1) + SumOfupDownTimeAtIndividualTrees
	prev=0
	totalTime=0
	for i in range(totalTrees):
		totalTime+=abs(Height[i]-prev)
		prev=Height[i]
	totalTime= (totalTrees) + (totalTrees-1) + totalTime
	return totalTime
	
n=int(input())
arr=[]
while n:
	temp=int(input())
	arr.append(temp)
	n-=1
print(calculateTime(arr,len(arr)))