#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t, p = 0, ans;
  scanf("%d", &n);
  ans = n + n - 1;
  for (int i = 0; i < n; i++) {
    scanf("%d", &t);
    int v = t - p;
    v = v < 0 ? -v : v;
    p = t;
    ans += v;
  }
  printf("%d\n", ans);
  return 0;
}
