#include <bits/stdc++.h>
using namespace std;
const int MAX = 1e6 + 6;
long long int arr[2000005], brr[2000005], crr[2000005];
void solve(int n, long long int arr[]) {
  int cnt = n + arr[0];
  for (int i = 1; i < n; i++) {
    cnt += abs(arr[i] - arr[i - 1]) + 1;
  }
  cout << cnt;
  return;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> arr[i];
  solve(n, arr);
  cout << endl;
}
