
import java.util.Scanner;
public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long K=sc.nextLong();
		long A=sc.nextLong();
		long B=sc.nextLong();
		for(int i=(int) A;i<=B;i++) {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");

		}
} import java.util.Scanner; Scanner java.util public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long K=sc.nextLong();
		long A=sc.nextLong();
		long B=sc.nextLong();
		for(int i=(int) A;i<=B;i++) {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");

		}
} Main @SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long K=sc.nextLong();
		long A=sc.nextLong();
		long B=sc.nextLong();
		for(int i=(int) A;i<=B;i++) {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");

		} main {
		Scanner sc=new Scanner(System.in);
		long K=sc.nextLong();
		long A=sc.nextLong();
		long B=sc.nextLong();
		for(int i=(int) A;i<=B;i++) {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");

		} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) long K=sc.nextLong(); K sc.nextLong() sc.nextLong sc long A=sc.nextLong(); A sc.nextLong() sc.nextLong sc long B=sc.nextLong(); B sc.nextLong() sc.nextLong sc for(int i=(int) A;i<=B;i++) {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		} int i=(int) A; int i=(int) A; i (int) A i<=B i B i++ i++ i {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		} {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		} if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			} i%K==0 i%K i K 0 {
				System.out.println("OK");
				System.exit(0);
			} System.out.println("OK") System.out.println System.out System System.out "OK" System.exit(0) System.exit System 0 System.out.println("NG") System.out.println System.out System System.out "NG" String[] args args public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long K=sc.nextLong();
		long A=sc.nextLong();
		long B=sc.nextLong();
		for(int i=(int) A;i<=B;i++) {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");

		}
} public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long K=sc.nextLong();
		long A=sc.nextLong();
		long B=sc.nextLong();
		for(int i=(int) A;i<=B;i++) {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");

		}
} Main

import java.util.Scanner;
public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long K=sc.nextLong();
		long A=sc.nextLong();
		long B=sc.nextLong();
		for(int i=(int) A;i<=B;i++) {
			if(i%K==0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");

		}
}
