#include <bits/stdc++.h>
using namespace std;
struct pt {
  long long x, y;
};
long double dist(pt a, pt b) {
  return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}
int cmpr(pt a, pt b) {
  if (a.x == b.x)
    return a.y < b.y;
  else
    return a.x < b.x;
}
long double chek(pt a, pt b, pt c) {
  return (a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y)) / 2;
}
long long a[1111111];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  for (long long i = 0; i < n; i++) cin >> a[i];
  if (n == 1) return cout << a[0] + 1, 0;
  long long ans = 0;
  long long now = 0;
  for (long long i = 0; i < n - 1; i++) {
    if (now <= a[i])
      ans += a[i] - now;
    else {
      ans += a[i - 1] - a[i];
    }
    now = a[i];
    ans++;
    ans++;
  }
  if (now <= a[n - 1])
    ans += a[n - 1] - now;
  else {
    ans += a[n - 2] - a[n - 1];
  }
  ans++;
  cout << ans;
  return 0;
}
