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 JavaScript (node.js v5.12) (judge verdict: Accepted)

var lines = [];

var n=0;
var k=0;

var readline = require('readline');
var rl = readline.createInterface({
  input:  process.stdin,
  output: process.stdout
});

rl.on('line',function(x){
  lines.push(x);
});

rl.on('close',function(){
  n = Number(lines[0].split(" ")[0]);
  k = Number(lines[0].split(" ")[1]);

  if(n%2===0){
    if((Math.floor(n/2))<k || k<0){console.log("NO");}
    else{console.log("YES");}
  }
  else{
    if((Math.floor(n/2)+1)<k || k<0){console.log("NO");}
    else{console.log("YES");}
}

});