Problem Description

Determine if it is possible to choose $ K $ different integers between $ 1 $ and $ N $ such that no two integers differ by $ 1 $.

Input Format

The input is given from the standard input in the following format:

$ N $ $ K $

Output Format

Output YES if it is possible to choose $ K $ integers, otherwise output NO.

Sample Input and Output

Sample Input #1

3 2

Sample Output #1

YES

Sample Input #2

5 5

Sample Output #2

NO

Sample Input #3

31 10

Sample Output #3

YES

Sample Input #4

10 90

Sample Output #4

NO

Notes/Hints

Constraints

• $1 \leq N, K \leq 100$
• $ N, K $ are integers

Sample Explanation 1

Choosing $ 1, 3 $ works.

见题面 Input 部分

见题面 Output 部分