#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int n;
  cin >> n;
  long long int ans = 0;
  long long int arr[n];
  for (long long int i = 0; i < n; i++) cin >> arr[i];
  int curr = 0;
  for (long long int i = 0; i < n; i++) {
    if (i == 0) {
      curr = arr[i];
      ans += arr[i] + 1;
    } else {
      if (curr <= arr[i]) {
        ans += arr[i] - curr;
        ans += 2;
        curr = arr[i];
      } else {
        ans += curr - arr[i];
        ans += 2;
        curr = arr[i];
      }
    }
  }
  cout << ans << endl;
  return 0;
}
