#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, a[100005], ans, smallest = INT_MAX;
  cin >> n;
  ans = 2 * n - 1;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    smallest = min(smallest, a[i]);
  }
  ans += a[0];
  for (int i = 0; i < n - 1; i++) {
    if (a[i] > a[i + 1])
      ans += (a[i] - a[i + 1]);
    else
      ans += (a[i + 1] - a[i]);
  }
  cout << ans << endl;
  return 0;
}
