#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 1;
int arr[maxn];
int main() {
  int n;
  cin >> n;
  int sum = 0, a = 0;
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
    sum += abs(a - arr[i]) + 2;
    a = arr[i];
  }
  cout << sum - 1;
  return 0;
}
