#include <bits/stdc++.h>
using namespace std;
int a[100000];
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", a + i);
  int ans, ch;
  ans = ch = a[0];
  ans++;
  for (int i = 1; i < n; i++) {
    if (ch < a[i]) {
      ans = ans + 1 + abs(a[i] - ch) + 1;
    } else {
      ans = ans + abs(a[i] - ch) + 2;
    }
    ch = a[i];
  }
  printf("%d", ans);
  return 0;
}
