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