Problem:
Score : 100 points

Problem Statement

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.

Sample Input 1

3 2

Sample Output 1

YES

We can choose 1 and 3.

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

Solution in Fortran (GNU Fortran 9.2.1) (judge verdict: Wrong Answer)

program minpro2019A
    implicit none
    integer(8)N,K
    read*,N,K
    if(K>N/2+mod(N,2))then
        print'(A)',"YES"
    else
        print'(A)',"NO"
    end if
end program minpro2019A