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
import collections

infile = sys.stdin.buffer
def gs()  : return infile.readline().rstrip()
def gi()  : return int(gs())
def gss() : return gs().split()
def gis() : return [int(x) for x in gss()]

MOD = 10 ** 9 + 7
INF = 10 ** 12

#RRRBGBRBBB
#BBBRR

def main(infn="") :
    global infile
    infile = open(infn,"r") if infn else open(sys.argv[1],"r") if len(sys.argv) > 1 else sys.stdin
    ######################################################################
    h = [gi() for _ in range(gi())]
    s = (2*sum(h) + len(h) -1)
    ans = 0
    cur = 0
    for i in range(len(h)):
        ans += h[i] - cur
        cur = h[i]
        if i < len(h)-1 and cur > h[i+1]:
            ans += abs(cur - h[i+1])
            cur = h[i+1]
    ans += len(h) -1
    ans += len(h)
    print (ans)
    ######################################################################
if __name__ == '__main__' :
    main()