#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 sum = arr[0] + 1;
  for (int i = 1; i < n; i++) {
    sum = sum + (abs(arr[i - 1] - arr[i]));
    sum = sum + 2;
  }
  cout << sum;
}
