//WeLoveGolf.java
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();

        int sum=b/k;
        int ans=k*sum;
        //System.out.println("sum"+sum);
        //System.out.println("ans"+ans);

        if(ans>=a){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
        sc.close();
    }
} import java.util.Scanner; Scanner java.util 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();

        int sum=b/k;
        int ans=k*sum;
        //System.out.println("sum"+sum);
        //System.out.println("ans"+ans);

        if(ans>=a){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
        sc.close();
    }
} 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();

        int sum=b/k;
        int ans=k*sum;
        //System.out.println("sum"+sum);
        //System.out.println("ans"+ans);

        if(ans>=a){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
        sc.close();
    } main {
		Scanner sc=new Scanner(System.in);
		int k=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();

        int sum=b/k;
        int ans=k*sum;
        //System.out.println("sum"+sum);
        //System.out.println("ans"+ans);

        if(ans>=a){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
        sc.close();
    } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int k=sc.nextInt(); k sc.nextInt() sc.nextInt sc int a=sc.nextInt(); a sc.nextInt() sc.nextInt sc int b=sc.nextInt(); b sc.nextInt() sc.nextInt sc int sum=b/k; sum b/k b k int ans=k*sum; ans k*sum k sum if(ans>=a){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        } ans>=a ans a {
            System.out.println("OK");
        } System.out.println("OK") System.out.println System.out System System.out "OK" {
            System.out.println("NG");
        } System.out.println("NG") System.out.println System.out System System.out "NG" sc.close() sc.close sc String args[] args
//WeLoveGolf.java
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();

        int sum=b/k;
        int ans=k*sum;
        //System.out.println("sum"+sum);
        //System.out.println("ans"+ans);

        if(ans>=a){
            System.out.println("OK");
        }
        else{
            System.out.println("NG");
        }
        sc.close();
    }
}