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*.
from sys import *
from math import *
from sys import stdin,stdout
from collections import *

int_arr = lambda : list(map(int,stdin.readline().strip().split()))
str_arr = lambda :list(map(str,stdin.readline().split()))
get_str = lambda : map(str,stdin.readline().strip().split())
get_int = lambda: map(int,stdin.readline().strip().split())
get_float = lambda : map(float,stdin.readline().strip().split())


mod = 1000000007
setrecursionlimit(1000)

time = 0
prev = 0
for _ in range(int(input())):
    h = int(input())
    if prev <= h:
        if prev:
            time += 1 
        time += (h - prev) + 1
        prev = h
    else:
        if prev:
            time += 1
        time += (prev - h) + 1
        prev = h
print(time)
