#include <bits/stdc++.h>
using namespace std;
void boost() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
}
void free() {
  freopen("A.in", "r", stdin);
  freopen("A.out", "w", stdout);
}
int a[100001];
int main() {
  boost();
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  long long ans = 1, h = a[0];
  ans += h;
  for (int i = 1; i < n; i++) {
    if (a[i] >= h)
      ans += (a[i] - h + 1), h = a[i];
    else if (a[i] < h)
      ans += (h - a[i] + 1), h = a[i];
    ans++;
  }
  cout << ans, exit(0);
}
