#include <bits/stdc++.h>
using namespace std;
long long int mod = 1000000007;
void dispvec(set<long long int> arr) {
  set<long long int>::iterator itr = arr.begin();
  while (itr != arr.end()) {
    cout << *itr << " ";
    itr++;
  }
  cout << endl;
}
struct CustomCompare {
  bool operator()(const pair<long long int, long long int> &i,
                  const pair<long long int, long long int> &j) {
    if (i.first == j.first) return i.first < j.first;
    return i.second < j.second;
  }
};
void solve() {
  int n;
  cin >> n;
  vector<long long int> arr(n);
  for (int i = 0; i < n; i++) cin >> arr[i];
  long long int sum = arr[0] + 1;
  int curr = arr[0];
  for (int i = 1; i < n; i++) {
    if (arr[i] < arr[i - 1]) {
      sum += arr[i - 1] - arr[i];
    } else if (arr[i] > arr[i - 1]) {
      sum += arr[i] - arr[i - 1];
    }
    sum += 2;
  }
  cout << sum << endl;
}
int main() {
  int t = 1;
  int i = 1;
  while (i <= t) {
    solve();
    i++;
  }
  return 0;
}
