题目描述
Determine if we can choose K different integers between 1 and N (inclusive) so that no two of them differ by 1.
Constraints
- $1\leq N,K\leq 100$
- N and K are integers.
Input
Input is given from Standard Input in the following format:
N K
Output
If we can choose K integers as above, print YES; otherwise, print NO.
Examples
Input
3 2
Output
YES
Input
5 5
Output
NO
Input
31 10
Output
YES
Input
10 90
Output
NO
输入格式
见题面
输出格式
见题面
样例输入
10 90
样例输出
NO