#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, i, n1, k, a;
  cin >> n >> n1;
  k = n + n1;
  for (i = 1; i < n; i++) {
    cin >> a;
    if (a > n1)
      k += 1 + a - n1;
    else if (a < n1)
      k += n1 - a + 1;
    else
      k++;
    n1 = a;
  }
  cout << k;
  return 0;
}
