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(){
  int N,K;
  int i,count = 0;
  
  do{
    scanf("%d %d", &N,&K);
  }while(N<0 ||N>100 || K<0 || K>100);
  
  for(i=1;i<=N;i+=2){
    count++;
  }
  
  if(count >= K){printf("ok\n");}
  else{printf("no\n");}
  
  return 0;
}