import java.util.Scanner;

public class Main {

	static long bignum = 1000000000+7;

	public static void main(String[] args){

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean flag = false;

		for(int i=a;i<b+1;i++) {
			if(i%k==0) {
				flag=true;
				break;
			}
		}

		if(flag) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}

	static long divn(int target, int times) {//10_9+7のあまり累乗版
		int sqtimes = (int)Math.sqrt(times);
		long ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		long holder = ans;
		ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans*holder)%(1000000000+7);
		}
		for(int i=0;i<times - sqtimes*sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		return ans;
	}

	static long div(long a) {//10_9+7のあまり
		if(a<0)a+=1000000000+7;
		return a%(1000000000+7);
	}

}
/*
class City{
	int order;
	int prefecture;
	int year;
	int number;
	City(int order,int prefecture, int year){
		this.order = order;
		this.prefecture = prefecture;
		this.year = year;
	}
}
*/ import java.util.Scanner; Scanner java.util public class Main {

	static long bignum = 1000000000+7;

	public static void main(String[] args){

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean flag = false;

		for(int i=a;i<b+1;i++) {
			if(i%k==0) {
				flag=true;
				break;
			}
		}

		if(flag) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}

	static long divn(int target, int times) {//10_9+7のあまり累乗版
		int sqtimes = (int)Math.sqrt(times);
		long ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		long holder = ans;
		ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans*holder)%(1000000000+7);
		}
		for(int i=0;i<times - sqtimes*sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		return ans;
	}

	static long div(long a) {//10_9+7のあまり
		if(a<0)a+=1000000000+7;
		return a%(1000000000+7);
	}

} Main static long bignum = 1000000000+7; bignum 1000000000+7 1000000000 7 public static void main(String[] args){

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean flag = false;

		for(int i=a;i<b+1;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 = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean flag = false;

		for(int i=a;i<b+1;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 = 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 boolean flag = false; flag false for(int i=a;i<b+1;i++) {
			if(i%k==0) {
				flag=true;
				break;
			}
		} 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;
				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 static long divn(int target, int times) {//10_9+7のあまり累乗版
		int sqtimes = (int)Math.sqrt(times);
		long ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		long holder = ans;
		ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans*holder)%(1000000000+7);
		}
		for(int i=0;i<times - sqtimes*sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		return ans;
	} divn {//10_9+7のあまり累乗版
		int sqtimes = (int)Math.sqrt(times);
		long ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		long holder = ans;
		ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans*holder)%(1000000000+7);
		}
		for(int i=0;i<times - sqtimes*sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		return ans;
	} int sqtimes = (int)Math.sqrt(times); sqtimes (int)Math.sqrt(times) Math.sqrt Math times long ans = 1; ans 1 for(int i =0;i<sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		} int i =0; int i =0; i 0 i<sqtimes i sqtimes i++ i++ i {
			ans = (ans * target)%(1000000000+7);
		} {
			ans = (ans * target)%(1000000000+7);
		} ans = (ans * target)%(1000000000+7) ans (ans * target)%(1000000000+7) (ans * target) ans target (1000000000+7) 1000000000 7 long holder = ans; holder ans ans = 1 ans 1 for(int i =0;i<sqtimes;i++) {
			ans = (ans*holder)%(1000000000+7);
		} int i =0; int i =0; i 0 i<sqtimes i sqtimes i++ i++ i {
			ans = (ans*holder)%(1000000000+7);
		} {
			ans = (ans*holder)%(1000000000+7);
		} ans = (ans*holder)%(1000000000+7) ans (ans*holder)%(1000000000+7) (ans*holder) ans holder (1000000000+7) 1000000000 7 for(int i=0;i<times - sqtimes*sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		} int i=0; int i=0; i 0 i<times - sqtimes*sqtimes i times - sqtimes*sqtimes times sqtimes*sqtimes sqtimes sqtimes i++ i++ i {
			ans = (ans * target)%(1000000000+7);
		} {
			ans = (ans * target)%(1000000000+7);
		} ans = (ans * target)%(1000000000+7) ans (ans * target)%(1000000000+7) (ans * target) ans target (1000000000+7) 1000000000 7 return ans; ans int target target int times times static long div(long a) {//10_9+7のあまり
		if(a<0)a+=1000000000+7;
		return a%(1000000000+7);
	} div {//10_9+7のあまり
		if(a<0)a+=1000000000+7;
		return a%(1000000000+7);
	} if(a<0)a+=1000000000+7; a<0 a 0 a+=1000000000+7 a 1000000000+7 1000000000 7 return a%(1000000000+7); a%(1000000000+7) a (1000000000+7) 1000000000 7 long a a public class Main {

	static long bignum = 1000000000+7;

	public static void main(String[] args){

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean flag = false;

		for(int i=a;i<b+1;i++) {
			if(i%k==0) {
				flag=true;
				break;
			}
		}

		if(flag) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}

	static long divn(int target, int times) {//10_9+7のあまり累乗版
		int sqtimes = (int)Math.sqrt(times);
		long ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		long holder = ans;
		ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans*holder)%(1000000000+7);
		}
		for(int i=0;i<times - sqtimes*sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		return ans;
	}

	static long div(long a) {//10_9+7のあまり
		if(a<0)a+=1000000000+7;
		return a%(1000000000+7);
	}

} public class Main {

	static long bignum = 1000000000+7;

	public static void main(String[] args){

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean flag = false;

		for(int i=a;i<b+1;i++) {
			if(i%k==0) {
				flag=true;
				break;
			}
		}

		if(flag) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}

	static long divn(int target, int times) {//10_9+7のあまり累乗版
		int sqtimes = (int)Math.sqrt(times);
		long ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		long holder = ans;
		ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans*holder)%(1000000000+7);
		}
		for(int i=0;i<times - sqtimes*sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		return ans;
	}

	static long div(long a) {//10_9+7のあまり
		if(a<0)a+=1000000000+7;
		return a%(1000000000+7);
	}

} Main
import java.util.Scanner;

public class Main {

	static long bignum = 1000000000+7;

	public static void main(String[] args){

		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		boolean flag = false;

		for(int i=a;i<b+1;i++) {
			if(i%k==0) {
				flag=true;
				break;
			}
		}

		if(flag) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}

	static long divn(int target, int times) {//10_9+7のあまり累乗版
		int sqtimes = (int)Math.sqrt(times);
		long ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		long holder = ans;
		ans = 1;
		for(int i =0;i<sqtimes;i++) {
			ans = (ans*holder)%(1000000000+7);
		}
		for(int i=0;i<times - sqtimes*sqtimes;i++) {
			ans = (ans * target)%(1000000000+7);
		}
		return ans;
	}

	static long div(long a) {//10_9+7のあまり
		if(a<0)a+=1000000000+7;
		return a%(1000000000+7);
	}

}
/*
class City{
	int order;
	int prefecture;
	int year;
	int number;
	City(int order,int prefecture, int year){
		this.order = order;
		this.prefecture = prefecture;
		this.year = year;
	}
}
*/
