import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int K = Integer.parseInt(sc.next());
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		boolean flag = false;
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				flag = true;
				break;
			}
		}
		if (flag) {
			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 = Integer.parseInt(sc.next());
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		boolean flag = false;
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				flag = true;
				break;
			}
		}
		if (flag) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int K = Integer.parseInt(sc.next());
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		boolean flag = false;
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				flag = true;
				break;
			}
		}
		if (flag) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int K = Integer.parseInt(sc.next());
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		boolean flag = false;
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				flag = true;
				break;
			}
		}
		if (flag) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int K = Integer.parseInt(sc.next()); K Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int A = Integer.parseInt(sc.next()); A Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int B = Integer.parseInt(sc.next()); B Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc boolean flag = false; flag false for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				flag = true;
				break;
			}
		} int i = A; int i = A; i A i <= B i B i++ i++ i {
			if (i % K == 0) {
				flag = true;
				break;
			}
		} {
			if (i % K == 0) {
				flag = true;
				break;
			}
		} if (i % K == 0) {
				flag = true;
				break;
			} i % K == 0 i % K i K 0 {
				flag = true;
				break;
			} flag = true flag true break; if (flag) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		} flag {
			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 = Integer.parseInt(sc.next());
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		boolean flag = false;
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				flag = true;
				break;
			}
		}
		if (flag) {
			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 = Integer.parseInt(sc.next());
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		boolean flag = false;
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				flag = true;
				break;
			}
		}
		if (flag) {
			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 = Integer.parseInt(sc.next());
		int A = Integer.parseInt(sc.next());
		int B = Integer.parseInt(sc.next());
		boolean flag = false;
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				flag = true;
				break;
			}
		}
		if (flag) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}
	}
}
