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