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*.
#!/usr/bin/env pypy3

from sys import stdin, stdout

def input(): return stdin.readline().strip()
def read_int_list(): return list(map(int, input().split()))
def read_int_tuple(): return tuple(map(int, input().split()))
def read_int(): return int(input())

### CODE HERE

arr = [read_int() for _ in range(read_int())]

y = 0
ret = 0

for i,a in enumerate(arr):
    if y > a:
        # print(f"move to jump height in {a-y} moves")
        ret += y - a
        y = a
    else:
        pass
        # print("move to jump height in 0 moves")

    if i > 0:
        # print("jump")
        ret += 1

    # print(f"move to top in {a-y} moves")
    ret += a-y
    y = a

    # print(f"eat in 1 moves")
    ret += 1

print(ret)