#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, temp, count = 0;
  vector<int> v;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> temp;
    v.push_back(temp);
  }
  count += v[0];
  for (int i = 1; i < n; i++) {
    count += abs(v[i] - v[i - 1]);
  }
  count += n;
  count += (n - 1);
  cout << count << endl;
  return 0;
}
