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++14 (GCC 5.4.1) (judge verdict: Runtime Error)

#include <cstring>
#include <iostream>

using namespace std;
int main()
{
 int element;
int vertex[5];
memset(vertex,0,5);
for(int i=0;i<6;i++)
{
cin>>element;
vertex[element]++;
}
for(int i=1;i<=4;i++)
{
if(vertex[i]>2)
{
	
cout<<"NO";
return 0;
}

}
cout<<"YES";
return 0;
}