#include <bits/stdc++.h>
using namespace std;
void swap(char* a, char* b) {
  char t = *a;
  *a = *b;
  *b = t;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  long long int n;
  cin >> n;
  long long int steps = n;
  long long int h;
  cin >> h;
  long long int preh = h;
  steps += h;
  for (int i = 1; i < n; i++) {
    cin >> h;
    if (h == preh) {
      steps++;
      preh = h;
    } else if (h < preh) {
      steps += preh - h + 1;
      preh = h;
    } else {
      steps += h - preh + 1;
      preh = h;
    }
  }
  cout << steps;
  return 0;
}
