import java.util.*;
public class Main{
    public static void main(String[] args) {
        int test;
        Scanner sc=new Scanner(System.in);
        //test=sc.nextInt();
     //   while(test-->0){
            int k;
            int a,b;
            k= sc.nextInt();
            a=sc.nextInt();
            b=sc.nextInt();
            if(a%k==0|| b%k==0){
                System.out.println("OK");
            }
            else {
                if((a/k)<(b/k)){
                    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