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 x,y,z,i;

z = 0;

scanf("%d %d", &x, &y);
if((x == y)||(x < y)){
	printf("NO");
	return (0);
}

for (i = 1; i <= x + 1; i++){
	printf("%d %d\n", i, z);
	z++;
	i ++;
}
if (z <= y){
	printf("NO");
}
else{
	printf("YES");
}
return (0);
}