import java.util.Scanner;

public class Main {
	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 jg = false;

		for (int num = A; num <= B; num++) {
			if(num%K==0) {
				jg=true;
			}
		}
		if(jg) {
			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();
		int A = sc.nextInt();
		int B = sc.nextInt();
		boolean jg = false;

		for (int num = A; num <= B; num++) {
			if(num%K==0) {
				jg=true;
			}
		}
		if(jg) {
			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();
		int A = sc.nextInt();
		int B = sc.nextInt();
		boolean jg = false;

		for (int num = A; num <= B; num++) {
			if(num%K==0) {
				jg=true;
			}
		}
		if(jg) {
			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 jg = false;

		for (int num = A; num <= B; num++) {
			if(num%K==0) {
				jg=true;
			}
		}
		if(jg) {
			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 jg = false; jg false for (int num = A; num <= B; num++) {
			if(num%K==0) {
				jg=true;
			}
		} int num = A; int num = A; num A num <= B num B num++ num++ num {
			if(num%K==0) {
				jg=true;
			}
		} {
			if(num%K==0) {
				jg=true;
			}
		} if(num%K==0) {
				jg=true;
			} num%K==0 num%K num K 0 {
				jg=true;
			} jg=true jg true if(jg) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		} jg {
			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();
		int A = sc.nextInt();
		int B = sc.nextInt();
		boolean jg = false;

		for (int num = A; num <= B; num++) {
			if(num%K==0) {
				jg=true;
			}
		}
		if(jg) {
			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();
		int A = sc.nextInt();
		int B = sc.nextInt();
		boolean jg = false;

		for (int num = A; num <= B; num++) {
			if(num%K==0) {
				jg=true;
			}
		}
		if(jg) {
			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();
		int A = sc.nextInt();
		int B = sc.nextInt();
		boolean jg = false;

		for (int num = A; num <= B; num++) {
			if(num%K==0) {
				jg=true;
			}
		}
		if(jg) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}

	}
}
