#CCBOTPBA0000046. Kiểm tra số tăng chữ số (Nondecreasing Decimal Digits)

Kiểm tra số tăng chữ số (Nondecreasing Decimal Digits)

Nondecreasing Decimal Digits

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

Determine whether the decimal digits of n are nondecreasing from left to right (equal neighboring digits allowed). Zero and single-digit values qualify.

Input

One integer n.

Output

Print YES or NO.

Subtasks

  • Subtask 1 (20%): n ≤ 999.

  • Subtask 2 (30%): n ≤ 10^9.

  • Subtask 3 (50%): n ≤ 10^18.

Examples

Example 1

Input:

11249

Output:

YES

Explanation: Equal neighboring digits are allowed.

Example 2

Input:

132

Output:

NO

Explanation: The pair 3 then 2 decreases.

Example 3

Input:

0

Output:

YES

Explanation: Zero has only one digit.