#include <bits/stdc++.h>
using namespace std;
int a[100001], n;
int main() {
  int i, h;
  scanf("%d\n", &n);
  for (i = 1; i <= n; ++i) scanf("%d\n", &a[i]);
  h = a[1];
  for (i = 2; i <= n; ++i)
    if (a[i - 1] < a[i])
      h += a[i] - a[i - 1] + 1;
    else
      h += a[i - 1] - a[i] + 1;
  h += n;
  printf("%d", h);
  return 0;
}
