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>
#include<math.h>
int main(void) {
    int N,K;
    int i,j;
    j=0;
    scanf("%d %d",&N,&K);
    for(i=1;i<=N;i++){
    	if(abs(N-i)!=1){
    		j++;
    	}
    }
    if(j>=K){
    	printf("YES\n");
    }else{
    	printf("NO\n");
    }
}