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: Wrong Answer)

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        int nValue; // 1 <= N
        int kValue; //<= 100
        int checkN; //

        Scanner scanner = new Scanner(System.in);
//
//        System.out.println("1 以上 N 以下の異なる整数を、差が 1 の整数をともに選ばないように K 個選びます");
//        System.out.println("NとKをそれぞれ半角空白で区切って入力してください");
//        System.out.println("例: input ->10 90");
//        System.out.println("input >>");

        String N = scanner.next();
        String K = scanner.next();

        try {
        nValue = Integer.parseInt(N);

        } catch (NumberFormatException e) {
//            System.out.println();
            return;
        }
        try {
        kValue = Integer.valueOf(K);

        } catch (NumberFormatException e) {
            return;
        }


        if (100 < kValue || kValue < 1) {
//            System.out.println("Kの値は1以上100以下の整数を入力してください。終了します。");
            return;
        }
        if (nValue < 2) {
//            System.out.println("Nの値は1以上の整数を入力してください。終了します。");
            return;
        }


        if (nValue % 2 == 1) {
            checkN = nValue + 1;
        } else {
            checkN = nValue;
        }

        if ((checkN  /  2) >= kValue ) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
        scanner.close();
    }
}