import java.util.*;class Main{public static void main(String[]a){Scanner s=new Scanner(System.in);int n=s.nextInt(),m=s.nextInt();System.out.print((s.nextInt()/n*n)>=m?"OK":"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