#include <bits/stdc++.h>
using namespace std;
void solution() {
  long long n, x, m = 0, ans = 0;
  cin >> n;
  ans += 2 * n - 1;
  while (n--) {
    cin >> x;
    ans += abs(x - m);
    m = x;
  }
  cout << ans << "\n";
}
int main() {
  ios ::sync_with_stdio(0);
  cin.tie(0);
  long long t;
  t = 1;
  while (t--) {
    solution();
  }
  return 0;
}
