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