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