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*.
import sys
def input():
    return sys.stdin.readline().strip()
 
 
def iinput():
    return int(input())
 
 
def tinput():
    return input().split()
 
 
def rinput():
    return map(int, tinput())
 
 
def rlinput():
    return list(rinput())

n = iinput()
A = [-1]*(n)
for i in range(n):
    A[i] = iinput()
cost = A[0]+1
for i in range(1,n):
    cost += 1 #jump 
    if A[i] >= A[i-1]:
        cost += (A[i]-A[i-1] + 1)
    else:
        cost += (A[i-1]-A[i]+1)
print(cost)