import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		int large = (b / k) * k;
	
		
		
		if(large >= a && large <= b) {
			System.out.println("OK");
		}
		else if(a == b && (k == 1 || k == a)) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
		
	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		int large = (b / k) * k;
	
		
		
		if(large >= a && large <= b) {
			System.out.println("OK");
		}
		else if(a == b && (k == 1 || k == a)) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
		
	}

} Main public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		int large = (b / k) * k;
	
		
		
		if(large >= a && large <= b) {
			System.out.println("OK");
		}
		else if(a == b && (k == 1 || k == a)) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
		
	} main {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		int large = (b / k) * k;
	
		
		
		if(large >= a && large <= b) {
			System.out.println("OK");
		}
		else if(a == b && (k == 1 || k == a)) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
		
	} 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 int large = (b / k) * k; large (b / k) * k (b / k) b k k if(large >= a && large <= b) {
			System.out.println("OK");
		}
		else if(a == b && (k == 1 || k == a)) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		} large >= a && large <= b large >= a large a large <= b large b {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" if(a == b && (k == 1 || k == a)) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		} a == b && (k == 1 || k == a) a == b a b (k == 1 || k == a) k == 1 k 1 k == a k a {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" {
			System.out.println("NG");
		} System.out.println("NG") System.out.println System.out System System.out "NG" String[] args args public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		int large = (b / k) * k;
	
		
		
		if(large >= a && large <= b) {
			System.out.println("OK");
		}
		else if(a == b && (k == 1 || k == a)) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
		
	}

} public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		int large = (b / k) * k;
	
		
		
		if(large >= a && large <= b) {
			System.out.println("OK");
		}
		else if(a == b && (k == 1 || k == a)) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
		
	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		
		Scanner scan = new Scanner(System.in);
		
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		
		int large = (b / k) * k;
	
		
		
		if(large >= a && large <= b) {
			System.out.println("OK");
		}
		else if(a == b && (k == 1 || k == a)) {
			System.out.println("OK");
		}
		else {
			System.out.println("NG");
		}
		
	}

}
