#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int n;
  cin >> n;
  long long int arr[n];
  long long int ans = n;
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
  }
  ans += arr[0];
  for (int i = 1; i < n; i++) {
    if (arr[i] > arr[i - 1]) {
      ans++;
      ans = ans + arr[i] - arr[i - 1];
    }
    if (arr[i] == arr[i - 1]) {
      ans++;
    }
    if (arr[i] < arr[i - 1]) {
      ans++;
      ans = ans + arr[i - 1] - arr[i];
    }
  }
  cout << ans;
  return 0;
}
