import java.util.*;

public class Main {

	public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		int K = keyboard.nextInt();
		int A = keyboard.nextInt();
		int B = keyboard.nextInt();
		
		String ans ="NG"; 
		for(int x=A; x<=B; x++) {
			if(x%K == 0)
			ans = "OK";
		}
		
		System.out.println(ans);
		keyboard.close();
	}
} import java.util.*; util.* java public class Main {

	public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		int K = keyboard.nextInt();
		int A = keyboard.nextInt();
		int B = keyboard.nextInt();
		
		String ans ="NG"; 
		for(int x=A; x<=B; x++) {
			if(x%K == 0)
			ans = "OK";
		}
		
		System.out.println(ans);
		keyboard.close();
	}
} Main public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		int K = keyboard.nextInt();
		int A = keyboard.nextInt();
		int B = keyboard.nextInt();
		
		String ans ="NG"; 
		for(int x=A; x<=B; x++) {
			if(x%K == 0)
			ans = "OK";
		}
		
		System.out.println(ans);
		keyboard.close();
	} main {

		Scanner keyboard = new Scanner(System.in);

		int K = keyboard.nextInt();
		int A = keyboard.nextInt();
		int B = keyboard.nextInt();
		
		String ans ="NG"; 
		for(int x=A; x<=B; x++) {
			if(x%K == 0)
			ans = "OK";
		}
		
		System.out.println(ans);
		keyboard.close();
	} Scanner keyboard = new Scanner(System.in); keyboard new Scanner(System.in) int K = keyboard.nextInt(); K keyboard.nextInt() keyboard.nextInt keyboard int A = keyboard.nextInt(); A keyboard.nextInt() keyboard.nextInt keyboard int B = keyboard.nextInt(); B keyboard.nextInt() keyboard.nextInt keyboard String ans ="NG"; ans "NG" for(int x=A; x<=B; x++) {
			if(x%K == 0)
			ans = "OK";
		} int x=A; int x=A; x A x<=B x B x++ x++ x {
			if(x%K == 0)
			ans = "OK";
		} {
			if(x%K == 0)
			ans = "OK";
		} if(x%K == 0)
			ans = "OK"; x%K == 0 x%K x K 0 ans = "OK" ans "OK" System.out.println(ans) System.out.println System.out System System.out ans keyboard.close() keyboard.close keyboard String[] args args public class Main {

	public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		int K = keyboard.nextInt();
		int A = keyboard.nextInt();
		int B = keyboard.nextInt();
		
		String ans ="NG"; 
		for(int x=A; x<=B; x++) {
			if(x%K == 0)
			ans = "OK";
		}
		
		System.out.println(ans);
		keyboard.close();
	}
} public class Main {

	public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		int K = keyboard.nextInt();
		int A = keyboard.nextInt();
		int B = keyboard.nextInt();
		
		String ans ="NG"; 
		for(int x=A; x<=B; x++) {
			if(x%K == 0)
			ans = "OK";
		}
		
		System.out.println(ans);
		keyboard.close();
	}
} Main
import java.util.*;

public class Main {

	public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		int K = keyboard.nextInt();
		int A = keyboard.nextInt();
		int B = keyboard.nextInt();
		
		String ans ="NG"; 
		for(int x=A; x<=B; x++) {
			if(x%K == 0)
			ans = "OK";
		}
		
		System.out.println(ans);
		keyboard.close();
	}
}
