#include <bits/stdc++.h>
using namespace std;
int n, sum;
int main() {
  cin >> n;
  int a[n];
  cin >> a[0];
  sum = (2 * n) - 1 + a[0];
  for (int i = 1; i < n; i++) {
    cin >> a[i];
    sum += abs(a[i] - a[i - 1]);
  }
  cout << sum;
}
