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;
  scanf("%d %d",&N,&K);

  if(N>=1 && K<=100){
   if(N>K){
      if(N%2==0){
        if(N/2>=K){
      printf("YES\n");
        }
         else {
         printf("NO\n");
          }}
      
       if(N%2==1){
        if((N+1)/2>=K){
      printf("YES\n");
        }      
        else {
         printf("NO\n");
          }}}
  else{
    printf("NO\n");
  }}
    return 0;
  }