#include <bits/stdc++.h>
int main() {
  int n;
  scanf("%d", &n);
  int p = 0;
  int a[100100];
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  int s = n + n - 1;
  for (int i = 0; i < n; i++) {
    s += fabs(a[i] - p);
    p = a[i];
  }
  printf("%d\n", s);
}
