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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
int main(void){
  int n, k, j, m, x;
  scanf("%d", &n);
  scanf("%d", &k);
  x = n % 2;
    if (x==1) {
      j=n/2;
    }else{
      m=n-1;
      j=m/2;
    }
    if (j<=k) {
      printf("YES");
    }else{
      printf("NO");
    }
  return 0;
}