#include <bits/stdc++.h>
using namespace std;
int main() {
  cin.tie(0);
  std::ios::sync_with_stdio(false);
  int n, z;
  long long sum = 0, last = 0, h = 0;
  vector<int> a;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> z;
    sum += (abs(z - last) + 1 + i - h);
    last = z;
    h = i;
  }
  cout << sum << endl;
  return 0;
}
