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