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