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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String s = in.readLine();
        String[] sArray = s.split(" ", 0);

        if (sArray.length != 2){
            System.out.println("Input argument error.");
            return;
        }

        int n = Integer.parseInt(sArray[0]);
        int k = Integer.parseInt(sArray[1]);

        int val = 1;
        int count = 1;
        while(val <= n){
            count++;
            val += 2;
        }

        if(count > k){
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}