Smooth contest#11358
Andrey doesn't like sharp drops, especially in contests. Two numbers and form a sharp drop if |a-b| > 1. The contest is considered smooth if no difficulties of two neighboring problems form a sharp drop.
You are given numbers — the complexity of the problems. Determine if these tasks form a smooth contest.
The first line contains five integers , , , , (1 \le a, b, c, d, e \le 10^6) — problem complexities.
Print «YES» if the numbers form a smooth contest, and «NO» otherwise (The checking system is case-insensitive, meaning responses like «Yes» and «yES» are also accepted).
Example 1
Example 2
Explanation for the first example:
|1-2| = 1, |2-2| = 0, |2-2| = 0, |2-1| = 1.
None of these pairs form a sharp drop, so the numbers \{1,2,2,2,1\} form a smooth contest.
Explanation for the second example: |1-2| = 1, |2-2| = 0, |2-1| = 1, |1-3| = 2.
As you can see, the last two numbers form a sharp drop, so the numbers \{1,2,2,1,3\} do not form a smooth contest.