#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> v(n);
  if (n == 1) {
    int t;
    cin >> t;
    cout << t + 1;
  } else {
    for (int i = 0; i < n; i++) cin >> v[i];
    long long cnt = 0;
    cnt += v[0] + 1;
    if (v[1] >= v[0]) {
      cnt += 2;
      cnt += v[1] - v[0];
    } else {
      cnt += v[0] - v[1];
      cnt += 2;
    }
    for (int i = 1; i < n - 1; i++) {
      if (v[i + 1] >= v[i]) {
        cnt += 2;
        cnt += v[i + 1] - v[i];
      } else {
        cnt += v[i] - v[i + 1];
        cnt += 2;
      }
    }
    cout << cnt;
  }
  return 0;
}
