#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  int time = 2 * n - 1;
  int prev;
  int temp;
  cin >> prev;
  time += prev;
  for (int i = 1; i < n; i++) {
    cin >> temp;
    if (temp >= prev) {
      time = time + temp - prev;
    } else {
      time = time + prev - temp;
    }
    prev = temp;
  }
  cout << time;
  return 0;
}
