
import java.util.*;
public class Main {// Main
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);


		int n = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int q = a/n;
		int q2 = b/n;
		if(q2>q || a%n==0) {
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
		
}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz