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: Accepted)

#include <iostream>
using namespace std;
int main(void){
    // Your code here!
    int n,k;
    
    cin>>n>>k;
        if(n%2==1 && (n+1)/k>=2) cout<<"YES"<<endl;
        else if(n%2==0 && (n/k)>=2)  cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    
    return 0;
    
}