import 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();
        for(int i = a; i <= b; i++){
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
        scan.close();
    }
} import java.util.*; util.* java 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();
        for(int i = a; i <= b; i++){
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
        scan.close();
    }
} 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();
        for(int i = a; i <= b; i++){
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
        scan.close();
    } main {
        Scanner scan = new Scanner(System.in);
        int k = scan.nextInt();
        int a = scan.nextInt();
        int b = scan.nextInt();
        for(int i = a; i <= b; i++){
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
        scan.close();
    } 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 for(int i = a; i <= b; i++){
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        } int i = a; int i = a; i a i <= b i b i++ i++ i {
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        } {
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        } if(i % k == 0) {
                System.out.println("OK");
                return;
            } i % k == 0 i % k i k 0 {
                System.out.println("OK");
                return;
            } System.out.println("OK") System.out.println System.out System System.out "OK" return; System.out.println("NG") System.out.println System.out System System.out "NG" scan.close() scan.close scan 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();
        for(int i = a; i <= b; i++){
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
        scan.close();
    }
} 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();
        for(int i = a; i <= b; i++){
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
        scan.close();
    }
} Main
import 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();
        for(int i = a; i <= b; i++){
            if(i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
        scan.close();
    }
}