import java.util.Scanner;


public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean ans = false;
		
		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				ans = true;
				break;
			}
		}

		System.out.println(ans ? "OK" : "NG");
		sc.close();
	}

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

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean ans = false;
		
		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				ans = true;
				break;
			}
		}

		System.out.println(ans ? "OK" : "NG");
		sc.close();
	}

} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean ans = false;
		
		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				ans = true;
				break;
			}
		}

		System.out.println(ans ? "OK" : "NG");
		sc.close();
	} main {

		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean ans = false;
		
		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				ans = true;
				break;
			}
		}

		System.out.println(ans ? "OK" : "NG");
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int k = sc.nextInt(); k sc.nextInt() sc.nextInt sc int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc boolean ans = false; ans false for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				ans = true;
				break;
			}
		} int i = a; int i = a; i a i <= b i b i++ i++ i {
			if(i % k == 0) {
				ans = true;
				break;
			}
		} {
			if(i % k == 0) {
				ans = true;
				break;
			}
		} if(i % k == 0) {
				ans = true;
				break;
			} i % k == 0 i % k i k 0 {
				ans = true;
				break;
			} ans = true ans true break; System.out.println(ans ? "OK" : "NG") System.out.println System.out System System.out ans ? "OK" : "NG" ans "OK" "NG" sc.close() sc.close sc String[] args args public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean ans = false;
		
		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				ans = true;
				break;
			}
		}

		System.out.println(ans ? "OK" : "NG");
		sc.close();
	}

} public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean ans = false;
		
		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				ans = true;
				break;
			}
		}

		System.out.println(ans ? "OK" : "NG");
		sc.close();
	}

} Main
import java.util.Scanner;


public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean ans = false;
		
		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				ans = true;
				break;
			}
		}

		System.out.println(ans ? "OK" : "NG");
		sc.close();
	}

}