import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
	}
} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
	} main {
		Scanner sc = new Scanner(System.in);
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		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 for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		} int i = A; int i = A; i A i <= B i B i++ i++ i {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		} {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		} if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			} i % K == 0 i % K i K 0 {
				System.out.println("OK");
				System.exit(0);
			} System.out.println("OK") System.out.println System.out System System.out "OK" System.exit(0) System.exit System 0 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) throws Exception {
		Scanner sc = new Scanner(System.in);
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
	}
} public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();
		for (int i = A; i <= B; i++) {
			if (i % K == 0) {
				System.out.println("OK");
				System.exit(0);
			}
		}
		System.out.println("NG");
	}
}