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();
		boolean bool = false;
		
		for(int i=a;i<=b;i++) {
			if(i % k == 0) {
				bool = true;
			}
		}
		
		if(bool) {
			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) {
		Scanner scan = new Scanner(System.in);
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		boolean bool = false;
		
		for(int i=a;i<=b;i++) {
			if(i % k == 0) {
				bool = true;
			}
		}
		
		if(bool) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}

} 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();
		boolean bool = false;
		
		for(int i=a;i<=b;i++) {
			if(i % k == 0) {
				bool = true;
			}
		}
		
		if(bool) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	} main {
		Scanner scan = new Scanner(System.in);
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		boolean bool = false;
		
		for(int i=a;i<=b;i++) {
			if(i % k == 0) {
				bool = true;
			}
		}
		
		if(bool) {
			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 boolean bool = false; bool false for(int i=a;i<=b;i++) {
			if(i % k == 0) {
				bool = true;
			}
		} int i=a; int i=a; i a i<=b i b i++ i++ i {
			if(i % k == 0) {
				bool = true;
			}
		} {
			if(i % k == 0) {
				bool = true;
			}
		} if(i % k == 0) {
				bool = true;
			} i % k == 0 i % k i k 0 {
				bool = true;
			} bool = true bool true if(bool) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		} bool {
			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) {
		Scanner scan = new Scanner(System.in);
		int k = scan.nextInt();
		int a = scan.nextInt();
		int b = scan.nextInt();
		boolean bool = false;
		
		for(int i=a;i<=b;i++) {
			if(i % k == 0) {
				bool = true;
			}
		}
		
		if(bool) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}

} 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();
		boolean bool = false;
		
		for(int i=a;i<=b;i++) {
			if(i % k == 0) {
				bool = true;
			}
		}
		
		if(bool) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}

} 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();
		boolean bool = false;
		
		for(int i=a;i<=b;i++) {
			if(i % k == 0) {
				bool = true;
			}
		}
		
		if(bool) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}

}
