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

void solve(){
	int n,k;
	scanf("%d%d",&n,&k);
	int ret = 0;
	for(int i=1;i<=n;i+=2){
		++ret;
	}
	if(ret>=k){
		printf("YES\n");
	} else {
		printf("NO\n");
	}
}
int main(){
	//freopen("input.txt","r",stdin);
	solve();
}