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)

/** source code by coolreshab **/

#include<bits/stdc++.h>
using namespace std;

#define MAX 100000
#define MAX1 100000
#define inf 1000000000
#define mod 1000000007
#define ll long long

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    //begin
    int n,k,x;
    cin>>n>>k;
    if(n&1)
    {
        x=n/2;
        x++;
    }
    else
        x=n/2;
    if(x>=k)
        cout<<"YES";
    else
        cout<<"NO";
    //end

    return 0;
}