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"
 
typedef long long ll;
#define int ll
#define fi first
#define se second
#define SORT(a) sort(a.begin(),a.end())
#define rep(i,n) for(int i = 0;i < (n) ; i++) 
#define REP(i,n) for(int i = 0;i < (n) ; i++) 
#define MP(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define INF LLONG_MAX/2

using namespace std;
int MOD = 1000000007;
signed main(){

    int n,k;
    cin >> n >> k;
    if(n+1 >= 2*k)cout << "YES";
    else cout << "NO";
    cout << endl;



    
    return 0;   
}
// g++ -std=c++14 code1.cpp
// rm -r -f test;oj dl https://ddcc2019-final.contest.atcoder.jp/tasks/ddcc2019_final_a
// rm -r -f test;oj dl http://arc060.contest.atcoder.jp/tasks/arc060_a