import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int K= sc.nextInt(),A=sc.nextInt(),B=sc.nextInt();
		boolean flag= false;
		for(int i=A;i<B+1;i++) {
			if(i%K==0) {
				flag=true;
			}
		}
		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= sc.nextInt(),A=sc.nextInt(),B=sc.nextInt();
		boolean flag= false;
		for(int i=A;i<B+1;i++) {
			if(i%K==0) {
				flag=true;
			}
		}
		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= sc.nextInt(),A=sc.nextInt(),B=sc.nextInt();
		boolean flag= false;
		for(int i=A;i<B+1;i++) {
			if(i%K==0) {
				flag=true;
			}
		}
		if(flag) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
		

	} main {
		Scanner sc = new Scanner(System.in);
		int K= sc.nextInt(),A=sc.nextInt(),B=sc.nextInt();
		boolean flag= false;
		for(int i=A;i<B+1;i++) {
			if(i%K==0) {
				flag=true;
			}
		}
		if(flag) {
			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 A=sc.nextInt() A sc.nextInt() sc.nextInt sc B=sc.nextInt(); B sc.nextInt() sc.nextInt sc boolean flag= false; flag false for(int i=A;i<B+1;i++) {
			if(i%K==0) {
				flag=true;
			}
		} int i=A; int i=A; i A i<B+1 i B+1 B 1 i++ i++ i {
			if(i%K==0) {
				flag=true;
			}
		} {
			if(i%K==0) {
				flag=true;
			}
		} if(i%K==0) {
				flag=true;
			} i%K==0 i%K i K 0 {
				flag=true;
			} flag=true flag true 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= sc.nextInt(),A=sc.nextInt(),B=sc.nextInt();
		boolean flag= false;
		for(int i=A;i<B+1;i++) {
			if(i%K==0) {
				flag=true;
			}
		}
		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= sc.nextInt(),A=sc.nextInt(),B=sc.nextInt();
		boolean flag= false;
		for(int i=A;i<B+1;i++) {
			if(i%K==0) {
				flag=true;
			}
		}
		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= sc.nextInt(),A=sc.nextInt(),B=sc.nextInt();
		boolean flag= false;
		for(int i=A;i<B+1;i++) {
			if(i%K==0) {
				flag=true;
			}
		}
		if(flag) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
		

	}

}
