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();
		int num = 0;

		for (int i = A; i <= B; i++){
			if (i % K == 0){
				num += 1;
			}
		}
		if (num > 0){
			System.out.println("OK");
		}else if (num == 0){
			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();
		int num = 0;

		for (int i = A; i <= B; i++){
			if (i % K == 0){
				num += 1;
			}
		}
		if (num > 0){
			System.out.println("OK");
		}else if (num == 0){
			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();
		int num = 0;

		for (int i = A; i <= B; i++){
			if (i % K == 0){
				num += 1;
			}
		}
		if (num > 0){
			System.out.println("OK");
		}else if (num == 0){
			System.out.println("NG");
		}
	} main {
		Scanner scan = new Scanner(System.in);
		int K = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();
		int num = 0;

		for (int i = A; i <= B; i++){
			if (i % K == 0){
				num += 1;
			}
		}
		if (num > 0){
			System.out.println("OK");
		}else if (num == 0){
			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 num = 0; num 0 for (int i = A; i <= B; i++){
			if (i % K == 0){
				num += 1;
			}
		} int i = A; int i = A; i A i <= B i B i++ i++ i {
			if (i % K == 0){
				num += 1;
			}
		} {
			if (i % K == 0){
				num += 1;
			}
		} if (i % K == 0){
				num += 1;
			} i % K == 0 i % K i K 0 {
				num += 1;
			} num += 1 num 1 if (num > 0){
			System.out.println("OK");
		}else if (num == 0){
			System.out.println("NG");
		} num > 0 num 0 {
			System.out.println("OK");
		} System.out.println("OK") System.out.println System.out System System.out "OK" if (num == 0){
			System.out.println("NG");
		} num == 0 num 0 {
			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();
		int num = 0;

		for (int i = A; i <= B; i++){
			if (i % K == 0){
				num += 1;
			}
		}
		if (num > 0){
			System.out.println("OK");
		}else if (num == 0){
			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();
		int num = 0;

		for (int i = A; i <= B; i++){
			if (i % K == 0){
				num += 1;
			}
		}
		if (num > 0){
			System.out.println("OK");
		}else if (num == 0){
			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();
		int num = 0;

		for (int i = A; i <= B; i++){
			if (i % K == 0){
				num += 1;
			}
		}
		if (num > 0){
			System.out.println("OK");
		}else if (num == 0){
			System.out.println("NG");
		}
	}
}