import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int m=sc.nextInt();
    int a=sc.nextInt();
    int b=sc.nextInt();
    if(a<=b){
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          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