import java.util.Scanner;

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

		String result = "NG";
		for(int i = 1; k * i <= b; i++) {
			if(k * i >= a) {
				result = "OK";
			}
		}
		System.out.println(result);
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Integer k = sc.nextInt();
		Integer a = sc.nextInt();
		Integer b = sc.nextInt();

		String result = "NG";
		for(int i = 1; k * i <= b; i++) {
			if(k * i >= a) {
				result = "OK";
			}
		}
		System.out.println(result);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Integer k = sc.nextInt();
		Integer a = sc.nextInt();
		Integer b = sc.nextInt();

		String result = "NG";
		for(int i = 1; k * i <= b; i++) {
			if(k * i >= a) {
				result = "OK";
			}
		}
		System.out.println(result);
	} main {
		Scanner sc = new Scanner(System.in);
		Integer k = sc.nextInt();
		Integer a = sc.nextInt();
		Integer b = sc.nextInt();

		String result = "NG";
		for(int i = 1; k * i <= b; i++) {
			if(k * i >= a) {
				result = "OK";
			}
		}
		System.out.println(result);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) Integer k = sc.nextInt(); k sc.nextInt() sc.nextInt sc Integer a = sc.nextInt(); a sc.nextInt() sc.nextInt sc Integer b = sc.nextInt(); b sc.nextInt() sc.nextInt sc String result = "NG"; result "NG" for(int i = 1; k * i <= b; i++) {
			if(k * i >= a) {
				result = "OK";
			}
		} int i = 1; int i = 1; i 1 k * i <= b k * i k i b i++ i++ i {
			if(k * i >= a) {
				result = "OK";
			}
		} {
			if(k * i >= a) {
				result = "OK";
			}
		} if(k * i >= a) {
				result = "OK";
			} k * i >= a k * i k i a {
				result = "OK";
			} result = "OK" result "OK" System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Integer k = sc.nextInt();
		Integer a = sc.nextInt();
		Integer b = sc.nextInt();

		String result = "NG";
		for(int i = 1; k * i <= b; i++) {
			if(k * i >= a) {
				result = "OK";
			}
		}
		System.out.println(result);
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Integer k = sc.nextInt();
		Integer a = sc.nextInt();
		Integer b = sc.nextInt();

		String result = "NG";
		for(int i = 1; k * i <= b; i++) {
			if(k * i >= a) {
				result = "OK";
			}
		}
		System.out.println(result);
	}
} Main
import java.util.Scanner;

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

		String result = "NG";
		for(int i = 1; k * i <= b; i++) {
			if(k * i >= a) {
				result = "OK";
			}
		}
		System.out.println(result);
	}
}