#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t;
  cin >> n;
  cin >> t;
  int count1 = t;
  int i = 1;
  for (int i = 0; i < n - 1; i++) {
    int x;
    cin >> x;
    if (t <= x) {
      count1 += 1 + 1 + x - t;
      t = x;
    } else {
      count1 += 1 + 1 + t - x;
      t = x;
    }
  }
  cout << count1 + 1;
  return 0;
}
