import java.util.Scanner;
public class Main {
    public static void main(String[] args){

        Scanner scan = new Scanner(System.in);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();
        String result = "NG";

        for (int i = A; i <= B; i++) {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        }
        System.out.println(result);
    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args){

        Scanner scan = new Scanner(System.in);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();
        String result = "NG";

        for (int i = A; i <= B; i++) {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        }
        System.out.println(result);
    }
} Main public static void main(String[] args){

        Scanner scan = new Scanner(System.in);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();
        String result = "NG";

        for (int i = A; i <= B; i++) {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        }
        System.out.println(result);
    } main {

        Scanner scan = new Scanner(System.in);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();
        String result = "NG";

        for (int i = A; i <= B; i++) {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        }
        System.out.println(result);
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int K = scan.nextInt(); K scan.nextInt() scan.nextInt scan int A = scan.nextInt(); A scan.nextInt() scan.nextInt scan int B = scan.nextInt(); B scan.nextInt() scan.nextInt scan String result = "NG"; result "NG" for (int i = A; i <= B; i++) {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        } int i = A; int i = A; i A i <= B i B i++ i++ i {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        } {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        } if (i % K == 0) {
                result= "OK";
                break;
            } i % K == 0 i % K i K 0 {
                result= "OK";
                break;
            } result= "OK" result "OK" break; System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
    public static void main(String[] args){

        Scanner scan = new Scanner(System.in);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();
        String result = "NG";

        for (int i = A; i <= B; i++) {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        }
        System.out.println(result);
    }
} public class Main {
    public static void main(String[] args){

        Scanner scan = new Scanner(System.in);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();
        String result = "NG";

        for (int i = A; i <= B; i++) {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        }
        System.out.println(result);
    }
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args){

        Scanner scan = new Scanner(System.in);
        int K = scan.nextInt();
        int A = scan.nextInt();
        int B = scan.nextInt();
        String result = "NG";

        for (int i = A; i <= B; i++) {
            if (i % K == 0) {
                result= "OK";
                break;
            }
        }
        System.out.println(result);
    }
}

