import java.util.Scanner;
 
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();
 
        if(a%k==0||b%k==0)
        {
            System.out.print("OK");
        }
        else
        if((b/k)-(a)/k>=1)
        {
            System.out.print("OK");
        }
        else
        {
            System.out.print("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