import java.util.Scanner;

/**
 * Main
 */
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();
        int count = 1;
        int flag = 0;   

        int Kbai = K;

        while (Kbai <= B) {
            if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            }
            count += 1;
            Kbai = K*count;
        }

        if(flag == 1){
            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();
        int count = 1;
        int flag = 0;   

        int Kbai = K;

        while (Kbai <= B) {
            if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            }
            count += 1;
            Kbai = K*count;
        }

        if(flag == 1){
            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();
        int count = 1;
        int flag = 0;   

        int Kbai = K;

        while (Kbai <= B) {
            if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            }
            count += 1;
            Kbai = K*count;
        }

        if(flag == 1){
            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();
        int count = 1;
        int flag = 0;   

        int Kbai = K;

        while (Kbai <= B) {
            if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            }
            count += 1;
            Kbai = K*count;
        }

        if(flag == 1){
            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 int count = 1; count 1 int flag = 0; flag 0 int Kbai = K; Kbai K while (Kbai <= B) {
            if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            }
            count += 1;
            Kbai = K*count;
        } Kbai <= B Kbai B {
            if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            }
            count += 1;
            Kbai = K*count;
        } if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            } Kbai >= A && Kbai <= B Kbai >= A Kbai A Kbai <= B Kbai B {
                flag = 1;
                break;
            } flag = 1 flag 1 break; count += 1 count 1 Kbai = K*count Kbai K*count K count if(flag == 1){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        } flag == 1 flag 1 {
            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();
        int count = 1;
        int flag = 0;   

        int Kbai = K;

        while (Kbai <= B) {
            if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            }
            count += 1;
            Kbai = K*count;
        }

        if(flag == 1){
            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();
        int count = 1;
        int flag = 0;   

        int Kbai = K;

        while (Kbai <= B) {
            if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            }
            count += 1;
            Kbai = K*count;
        }

        if(flag == 1){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    }
} Main
import java.util.Scanner;

/**
 * Main
 */
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();
        int count = 1;
        int flag = 0;   

        int Kbai = K;

        while (Kbai <= B) {
            if(Kbai >= A && Kbai <= B){
                flag = 1;
                break;
            }
            count += 1;
            Kbai = K*count;
        }

        if(flag == 1){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    }
}