#include <bits/stdc++.h>
int calc(int a, int b) {
  int c;
  if (a > b) {
    c = a - b + 1;
  } else {
    c = b - a + 1;
  }
  return c;
}
int main() {
  int n;
  scanf("%d", &n);
  int data[n];
  int i = 0;
  while (i < n) {
    scanf("%d", &data[i]);
    i++;
  }
  int ans = data[0] + n;
  int j = 0;
  while (j < n - 1) {
    ans += calc(data[j], data[j + 1]);
    j++;
  }
  printf("%d", ans);
  return 0;
}
