import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		if(b-a+1 < k) 
			if(a%k > 0 &&  a%k <= b%k) {
				System.out.println("NG");
				return;
			}
		
		System.out.println("OK");
	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		if(b-a+1 < k) 
			if(a%k > 0 &&  a%k <= b%k) {
				System.out.println("NG");
				return;
			}
		
		System.out.println("OK");
	}

} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		if(b-a+1 < k) 
			if(a%k > 0 &&  a%k <= b%k) {
				System.out.println("NG");
				return;
			}
		
		System.out.println("OK");
	} main {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		if(b-a+1 < k) 
			if(a%k > 0 &&  a%k <= b%k) {
				System.out.println("NG");
				return;
			}
		
		System.out.println("OK");
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int k = scan.nextInt(); k scan.nextInt() scan.nextInt scan int a = scan.nextInt(); a scan.nextInt() scan.nextInt scan int b = scan.nextInt(); b scan.nextInt() scan.nextInt scan if(b-a+1 < k) 
			if(a%k > 0 &&  a%k <= b%k) {
				System.out.println("NG");
				return;
			} b-a+1 < k b-a+1 b-a b a 1 k if(a%k > 0 &&  a%k <= b%k) {
				System.out.println("NG");
				return;
			} a%k > 0 &&  a%k <= b%k a%k > 0 a%k a k 0 a%k <= b%k a%k a k b%k b k {
				System.out.println("NG");
				return;
			} System.out.println("NG") System.out.println System.out System System.out "NG" return; System.out.println("OK") System.out.println System.out System System.out "OK" String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		if(b-a+1 < k) 
			if(a%k > 0 &&  a%k <= b%k) {
				System.out.println("NG");
				return;
			}
		
		System.out.println("OK");
	}

} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		if(b-a+1 < k) 
			if(a%k > 0 &&  a%k <= b%k) {
				System.out.println("NG");
				return;
			}
		
		System.out.println("OK");
	}

} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		if(b-a+1 < k) 
			if(a%k > 0 &&  a%k <= b%k) {
				System.out.println("NG");
				return;
			}
		
		System.out.println("OK");
	}

}