#include <bits/stdc++.h>
using namespace std;
int abs1(int a) { return a > 0 ? a : -a; }
int main() {
  ios_base::sync_with_stdio(0);
  int n, i, v, p = 0;
  long long s = -1;
  cin >> n;
  for (i = 1; i <= n; i++) {
    cin >> v;
    s += abs1(v - p) + 2;
    p = v;
  }
  cout << s;
  return 0;
}
