import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int K, A, B;

		K = sc.nextInt();
		A = sc.nextInt();
		B = sc.nextInt();

		int min, max, flg;

		min = A / K;
		max = B / K;
		flg = 0;

		for (int i = min; i <= max; i++) {
			if (K * i >= A && K * i <= B)
				flg = 1;
		}
		if(flg==1) 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, A, B;

		K = sc.nextInt();
		A = sc.nextInt();
		B = sc.nextInt();

		int min, max, flg;

		min = A / K;
		max = B / K;
		flg = 0;

		for (int i = min; i <= max; i++) {
			if (K * i >= A && K * i <= B)
				flg = 1;
		}
		if(flg==1) System.out.println("OK");
		else System.out.println("NG");
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int K, A, B;

		K = sc.nextInt();
		A = sc.nextInt();
		B = sc.nextInt();

		int min, max, flg;

		min = A / K;
		max = B / K;
		flg = 0;

		for (int i = min; i <= max; i++) {
			if (K * i >= A && K * i <= B)
				flg = 1;
		}
		if(flg==1) System.out.println("OK");
		else System.out.println("NG");
	} main {
		Scanner sc = new Scanner(System.in);

		int K, A, B;

		K = sc.nextInt();
		A = sc.nextInt();
		B = sc.nextInt();

		int min, max, flg;

		min = A / K;
		max = B / K;
		flg = 0;

		for (int i = min; i <= max; i++) {
			if (K * i >= A && K * i <= B)
				flg = 1;
		}
		if(flg==1) System.out.println("OK");
		else System.out.println("NG");
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int K K A A B; B 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 int min min max max flg; flg min = A / K min A / K A K max = B / K max B / K B K flg = 0 flg 0 for (int i = min; i <= max; i++) {
			if (K * i >= A && K * i <= B)
				flg = 1;
		} int i = min; int i = min; i min i <= max i max i++ i++ i {
			if (K * i >= A && K * i <= B)
				flg = 1;
		} {
			if (K * i >= A && K * i <= B)
				flg = 1;
		} if (K * i >= A && K * i <= B)
				flg = 1; K * i >= A && K * i <= B K * i >= A K * i K i A K * i <= B K * i K i B flg = 1 flg 1 if(flg==1) System.out.println("OK");
		else System.out.println("NG"); flg==1 flg 1 System.out.println("OK") System.out.println System.out System System.out "OK" 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, A, B;

		K = sc.nextInt();
		A = sc.nextInt();
		B = sc.nextInt();

		int min, max, flg;

		min = A / K;
		max = B / K;
		flg = 0;

		for (int i = min; i <= max; i++) {
			if (K * i >= A && K * i <= B)
				flg = 1;
		}
		if(flg==1) 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, A, B;

		K = sc.nextInt();
		A = sc.nextInt();
		B = sc.nextInt();

		int min, max, flg;

		min = A / K;
		max = B / K;
		flg = 0;

		for (int i = min; i <= max; i++) {
			if (K * i >= A && K * i <= B)
				flg = 1;
		}
		if(flg==1) 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, A, B;

		K = sc.nextInt();
		A = sc.nextInt();
		B = sc.nextInt();

		int min, max, flg;

		min = A / K;
		max = B / K;
		flg = 0;

		for (int i = min; i <= max; i++) {
			if (K * i >= A && K * i <= B)
				flg = 1;
		}
		if(flg==1) System.out.println("OK");
		else System.out.println("NG");
	}
}
