p03129 Yahoo Programming Contest 2019 - Anti-Adjacency_16997
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
n, k = map(int, raw_input().split())
if k == 1:
    print "YES"
else:
    print "YES" if n >= 2 * k - 1 else "NO"
