import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        Boolean flag = true;
        for(int i = A; i <= B; i++){
            if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            }
        }
        if(flag){
            System.out.print("NG");
        }
    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        Boolean flag = true;
        for(int i = A; i <= B; i++){
            if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            }
        }
        if(flag){
            System.out.print("NG");
        }
    }
} Main public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        Boolean flag = true;
        for(int i = A; i <= B; i++){
            if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            }
        }
        if(flag){
            System.out.print("NG");
        }
    } main {
        Scanner in = new Scanner(System.in);
        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        Boolean flag = true;
        for(int i = A; i <= B; i++){
            if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            }
        }
        if(flag){
            System.out.print("NG");
        }
    } Scanner in = new Scanner(System.in); in new Scanner(System.in) int K = in.nextInt(); K in.nextInt() in.nextInt in int A = in.nextInt(); A in.nextInt() in.nextInt in int B = in.nextInt(); B in.nextInt() in.nextInt in Boolean flag = true; flag true for(int i = A; i <= B; i++){
            if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            }
        } int i = A; int i = A; i A i <= B i B i++ i++ i {
            if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            }
        } {
            if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            }
        } if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            } i%K==0 i%K i K 0 {
                System.out.print("OK");
                flag = false;
                break;
            } System.out.print("OK") System.out.print System.out System System.out "OK" flag = false flag false break; if(flag){
            System.out.print("NG");
        } flag {
            System.out.print("NG");
        } System.out.print("NG") System.out.print System.out System System.out "NG" String[] args args public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        Boolean flag = true;
        for(int i = A; i <= B; i++){
            if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            }
        }
        if(flag){
            System.out.print("NG");
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int K = in.nextInt();
        int A = in.nextInt();
        int B = in.nextInt();
        Boolean flag = true;
        for(int i = A; i <= B; i++){
            if(i%K==0){
                System.out.print("OK");
                flag = false;
                break;
            }
        }
        if(flag){
            System.out.print("NG");
        }
    }
} Main
import java.util.Scanner;

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

