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