import 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();
		String str = null;
		for(int i = A;i <= B;i++) {
			if(i % K == 0) {
				str = "OK";
			}
		}
		if(str != null) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} import java.util.*; util.* java 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();
		String str = null;
		for(int i = A;i <= B;i++) {
			if(i % K == 0) {
				str = "OK";
			}
		}
		if(str != null) {
			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();
		String str = null;
		for(int i = A;i <= B;i++) {
			if(i % K == 0) {
				str = "OK";
			}
		}
		if(str != null) {
			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();
		String str = null;
		for(int i = A;i <= B;i++) {
			if(i % K == 0) {
				str = "OK";
			}
		}
		if(str != null) {
			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 String str = null; str null for(int i = A;i <= B;i++) {
			if(i % K == 0) {
				str = "OK";
			}
		} int i = A; int i = A; i A i <= B i B i++ i++ i {
			if(i % K == 0) {
				str = "OK";
			}
		} {
			if(i % K == 0) {
				str = "OK";
			}
		} if(i % K == 0) {
				str = "OK";
			} i % K == 0 i % K i K 0 {
				str = "OK";
			} str = "OK" str "OK" if(str != null) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		} str != null str null {
			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();
		String str = null;
		for(int i = A;i <= B;i++) {
			if(i % K == 0) {
				str = "OK";
			}
		}
		if(str != null) {
			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();
		String str = null;
		for(int i = A;i <= B;i++) {
			if(i % K == 0) {
				str = "OK";
			}
		}
		if(str != null) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
} Main
import 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();
		String str = null;
		for(int i = A;i <= B;i++) {
			if(i % K == 0) {
				str = "OK";
			}
		}
		if(str != null) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
}