#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> v(n);
  for (int i = 0; i < n; i++) cin >> v[i];
  int sum = v[0];
  for (int i = 1; i < n; i++)
    sum += v[i] + v[i - 1] - 2 * min(v[i], v[i - 1]) + 1;
  cout << sum + n;
}
