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();
		int g = 0;

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				g = 1;
				break;
			}
		}
		if(g == 1) {
			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 sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int g = 0;

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				g = 1;
				break;
			}
		}
		if(g == 1) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} 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();
		int g = 0;

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				g = 1;
				break;
			}
		}
		if(g == 1) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	} main {
		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int g = 0;

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				g = 1;
				break;
			}
		}
		if(g == 1) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	} 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 int g = 0; g 0 for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				g = 1;
				break;
			}
		} int i = a; int i = a; i a i <= b i b i++ i++ i {
			if(i % k == 0) {
				g = 1;
				break;
			}
		} {
			if(i % k == 0) {
				g = 1;
				break;
			}
		} if(i % k == 0) {
				g = 1;
				break;
			} i % k == 0 i % k i k 0 {
				g = 1;
				break;
			} g = 1 g 1 break; if(g == 1) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		} g == 1 g 1 {
			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 sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int g = 0;

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				g = 1;
				break;
			}
		}
		if(g == 1) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} 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();
		int g = 0;

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				g = 1;
				break;
			}
		}
		if(g == 1) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} 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();
		int g = 0;

		for(int i = a; i <= b; i++) {
			if(i % k == 0) {
				g = 1;
				break;
			}
		}
		if(g == 1) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
}
