#include <bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[]) {
  int n;
  cin >> n;
  int ara[100010];
  for (int i = 1; i <= n; i++) {
    cin >> ara[i];
  }
  int ans = 0;
  int temp = 0;
  for (int i = 1; i <= n; i++) {
    ans += abs(ara[i] - temp);
    temp = ara[i];
  }
  cout << ans + 2 * n - 1 << endl;
  return 0;
}
