#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int a[100000], n, t = 0;
  scanf("%lld", &n);
  for (int i = 0; i < n; i++) scanf("%lld", &a[i]);
  t += a[0] + 1;
  for (int i = 0; i < n - 1; i++) {
    if (a[i] > a[i + 1])
      t += (a[i] - a[i + 1]) + 2;
    else
      t += 1 + (a[i + 1] - a[i]) + 1;
  }
  printf("%lld\n", t);
  return 0;
}
