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