Problem:
Score: 100 points

Problem Statement

Takahashi the Jumbo will practice golf.

His objective is to get a carry distance that is a multiple of K, while he can only make a carry distance of between A and B (inclusive).

If he can achieve the objective, print OK; if he cannot, print NG.

Constraints

All values in input are integers.

1 \leq A \leq B \leq 1000

1 \leq K \leq 1000

Input

Input is given from Standard Input in the following format:

K
A B

Output

If he can achieve the objective, print OK; if he cannot, print NG.

Sample Input 1

7
500 600

Sample Output 1

OK

Among the multiples of 7, for example, 567 lies between 500 and 600.

Sample Input 2

4
5 7

Sample Output 2

NG

No multiple of 4 lies between 5 and 7.

Sample Input 3

1
11 11

Sample Output 3

OK

Solution in PHP (7.4.4) (judge verdict: Accepted)

<?php
$K = fgets(STDIN);  
  // 標準入力（STDIN）から1行読み込み（fgets）をしてinputに代入します
$input = fgets(STDIN);  // $input = "1 2 3 4 5"

// 取得した値を半角スペースで分解します（PHPのsplit的な関数） とりあえずこれで十分扱えます!
$input_array = explode(" ", $input); // $input_array = [ "1" , "2" , "3" , "4" , "5"]

$i = 0;
while(true){
  if($i * $K >= $input_array[0]){
    if($i * $K <= $input_array[1]){
      echo 'OK';
      return;
    }
    echo 'NG';
    return;
  }
  $i++;
}