#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int arr[n];
  for (int i = 0; i < n; i++) cin >> arr[i];
  int co = 0;
  for (int i = 0; i < n - 1; i++) {
    if (i == 0) co += arr[i];
    co += ((abs(arr[i] - arr[i + 1])) + 1);
  }
  co += n;
  if (n == 1) co = 2;
  cout << co << endl;
  return 0;
}
