import java.util.Scanner;

public 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.println("OK");
        }else{

        if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        }}
        



    }


}


 import java.util.Scanner; Scanner java.util public 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.println("OK");
        }else{

        if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        }}
        



    }


} 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.println("OK");
        }else{

        if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        }}
        



    } main {


        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.println("OK");
        }else{

        if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        }}
        



    } 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 if(A%K==0 || B%K==0){
            System.out.println("OK");
        }else{

        if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        }} A%K==0 || B%K==0 A%K==0 A%K A K 0 B%K==0 B%K B K 0 {
            System.out.println("OK");
        } System.out.println("OK") System.out.println System.out System System.out "OK" {

        if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        }} if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        } (B-A)>=K (B-A) B A K {
            System.out.println("OK");
        } System.out.println("OK") System.out.println System.out System System.out "OK" {
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        } int p = A%K; p A%K A K if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            } (K-p)<=(B-A) (K-p) K p (B-A) B 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" String[] args args public 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.println("OK");
        }else{

        if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        }}
        



    }


} public 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.println("OK");
        }else{

        if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        }}
        



    }


} Main
import java.util.Scanner;

public 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.println("OK");
        }else{

        if((B-A)>=K){
            System.out.println("OK");
        }else{
            int p = A%K;
            if((K-p)<=(B-A)){
                System.out.println("OK");
            }else {
                System.out.println("NG");
            }
        }}
        



    }


}



