import java.util.Scanner;


class Main{
 public static void main(String[] args){
 Scanner stdIn = new Scanner(System.in);
 //数値の入力
 int K = stdIn.nextInt(); //倍数
 int A = stdIn.nextInt();
 int B = stdIn.nextInt();
 
 //計算
 int num = 0;
 
 for (int i = 0; i <= (B / K); i++){
   if( i * K >= A)
    num = num +1;
 }
 
 if(num > 0)
  System.out.println("OK");
 else
  System.out.println("NG");
 }
} import java.util.Scanner; Scanner java.util class Main{
 public static void main(String[] args){
 Scanner stdIn = new Scanner(System.in);
 //数値の入力
 int K = stdIn.nextInt(); //倍数
 int A = stdIn.nextInt();
 int B = stdIn.nextInt();
 
 //計算
 int num = 0;
 
 for (int i = 0; i <= (B / K); i++){
   if( i * K >= A)
    num = num +1;
 }
 
 if(num > 0)
  System.out.println("OK");
 else
  System.out.println("NG");
 }
} Main public static void main(String[] args){
 Scanner stdIn = new Scanner(System.in);
 //数値の入力
 int K = stdIn.nextInt(); //倍数
 int A = stdIn.nextInt();
 int B = stdIn.nextInt();
 
 //計算
 int num = 0;
 
 for (int i = 0; i <= (B / K); i++){
   if( i * K >= A)
    num = num +1;
 }
 
 if(num > 0)
  System.out.println("OK");
 else
  System.out.println("NG");
 } main {
 Scanner stdIn = new Scanner(System.in);
 //数値の入力
 int K = stdIn.nextInt(); //倍数
 int A = stdIn.nextInt();
 int B = stdIn.nextInt();
 
 //計算
 int num = 0;
 
 for (int i = 0; i <= (B / K); i++){
   if( i * K >= A)
    num = num +1;
 }
 
 if(num > 0)
  System.out.println("OK");
 else
  System.out.println("NG");
 } Scanner stdIn = new Scanner(System.in); stdIn new Scanner(System.in) int K = stdIn.nextInt(); K stdIn.nextInt() stdIn.nextInt stdIn int A = stdIn.nextInt(); A stdIn.nextInt() stdIn.nextInt stdIn int B = stdIn.nextInt(); B stdIn.nextInt() stdIn.nextInt stdIn int num = 0; num 0 for (int i = 0; i <= (B / K); i++){
   if( i * K >= A)
    num = num +1;
 } int i = 0; int i = 0; i 0 i <= (B / K) i (B / K) B K i++ i++ i {
   if( i * K >= A)
    num = num +1;
 } {
   if( i * K >= A)
    num = num +1;
 } if( i * K >= A)
    num = num +1; i * K >= A i * K i K A num = num +1 num num +1 num 1 if(num > 0)
  System.out.println("OK");
 else
  System.out.println("NG"); num > 0 num 0 System.out.println("OK") System.out.println System.out System System.out "OK" System.out.println("NG") System.out.println System.out System System.out "NG" String[] args args
import java.util.Scanner;


class Main{
 public static void main(String[] args){
 Scanner stdIn = new Scanner(System.in);
 //数値の入力
 int K = stdIn.nextInt(); //倍数
 int A = stdIn.nextInt();
 int B = stdIn.nextInt();
 
 //計算
 int num = 0;
 
 for (int i = 0; i <= (B / K); i++){
   if( i * K >= A)
    num = num +1;
 }
 
 if(num > 0)
  System.out.println("OK");
 else
  System.out.println("NG");
 }
}
