Anti-Adjacency

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

inputFormat

Input

Input is given from Standard Input in the following format:

N K

outputFormat

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

样例

10 90

NO