    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 (b/k>(a-1)/k){
                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 (b/k>(a-1)/k){
                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 (b/k>(a-1)/k){
                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 (b/k>(a-1)/k){
                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 (b/k>(a-1)/k){
                System.out.println("OK");
            } else {
                System.out.println("NG");
            } b/k>(a-1)/k b/k b k (a-1)/k (a-1) a 1 k {
                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 (b/k>(a-1)/k){
                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 (b/k>(a-1)/k){
                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 (b/k>(a-1)/k){
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        }
    }