#include <bits/stdc++.h>
using namespace std;
long long n, a[101010], ans = 0;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  cin >> n;
  for (long long i = 0; i < n; ++i) cin >> a[i];
  ans = 2 * n - 1 + a[0];
  for (long long i = 1; i < n; ++i) {
    ans += abs(a[i] - a[i - 1]);
  }
  cout << ans << endl;
  return 0;
}
