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,i,j,count=0;
	
	scanf("%d %d",&n,&k);
	
	for(i=1;i<n;i++){
		for(j=1;i!=1&&j<i;j++){
			if(i!=j+1&&i!=j-1){
				count++;
			}
		}
	}
	if(count>=k){
		puts("YES");
	}else{
		puts("NO");
	}
	
	return 0;
}