import java.util.Scanner;
public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int k=sc.nextInt();
		int a=sc.nextInt();
		int b=sc.nextInt();
		System.out.println((b-b%k>=a)?"OK":"NG");
	}
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int k=sc.nextInt();
		int a=sc.nextInt();
		int b=sc.nextInt();
		System.out.println((b-b%k>=a)?"OK":"NG");
	}
} Main public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int k=sc.nextInt();
		int a=sc.nextInt();
		int b=sc.nextInt();
		System.out.println((b-b%k>=a)?"OK":"NG");
	} main {
		Scanner sc=new Scanner(System.in);
		int k=sc.nextInt();
		int a=sc.nextInt();
		int b=sc.nextInt();
		System.out.println((b-b%k>=a)?"OK":"NG");
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int k=sc.nextInt(); k sc.nextInt() sc.nextInt sc int a=sc.nextInt(); a sc.nextInt() sc.nextInt sc int b=sc.nextInt(); b sc.nextInt() sc.nextInt sc System.out.println((b-b%k>=a)?"OK":"NG") System.out.println System.out System System.out (b-b%k>=a)?"OK":"NG" (b-b%k>=a) b-b%k b b%k b k a "OK" "NG" String[] args args public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int k=sc.nextInt();
		int a=sc.nextInt();
		int b=sc.nextInt();
		System.out.println((b-b%k>=a)?"OK":"NG");
	}
} public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int k=sc.nextInt();
		int a=sc.nextInt();
		int b=sc.nextInt();
		System.out.println((b-b%k>=a)?"OK":"NG");
	}
} Main
import java.util.Scanner;
public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int k=sc.nextInt();
		int a=sc.nextInt();
		int b=sc.nextInt();
		System.out.println((b-b%k>=a)?"OK":"NG");
	}
}