import java.util.Scanner;

public class Main {

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

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

public class Main {

	public static void main(String[] args) {
		Scanner a = new Scanner(System.in);		
		int K = a.nextInt();
		int A = a.nextInt();
		int B = a.nextInt();
		int num = 0;
		for(int i = A ; i <= B; i++) {
			if(i % K == 0) {
				num++;
			}
		}
		if(num > 0) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
}