import java.util.*;

class Main {
    public static void main(String args[]) {
        Scanner inp = new Scanner(System.in);
        do_(inp);
        inp.close();
    }
    public static void do_(Scanner inp) {
        int k = inp.nextInt();
        int a = inp.nextInt();
        int b = inp.nextInt();
        for (int i = a; i <= b; i++) {
            if (i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} import java.util.*; util.* java class Main {
    public static void main(String args[]) {
        Scanner inp = new Scanner(System.in);
        do_(inp);
        inp.close();
    }
    public static void do_(Scanner inp) {
        int k = inp.nextInt();
        int a = inp.nextInt();
        int b = inp.nextInt();
        for (int i = a; i <= b; i++) {
            if (i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} Main public static void main(String args[]) {
        Scanner inp = new Scanner(System.in);
        do_(inp);
        inp.close();
    } main {
        Scanner inp = new Scanner(System.in);
        do_(inp);
        inp.close();
    } Scanner inp = new Scanner(System.in); inp new Scanner(System.in) do_(inp) do_ inp inp.close() inp.close inp String args[] args public static void do_(Scanner inp) {
        int k = inp.nextInt();
        int a = inp.nextInt();
        int b = inp.nextInt();
        for (int i = a; i <= b; i++) {
            if (i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    } do_ {
        int k = inp.nextInt();
        int a = inp.nextInt();
        int b = inp.nextInt();
        for (int i = a; i <= b; i++) {
            if (i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    } int k = inp.nextInt(); k inp.nextInt() inp.nextInt inp int a = inp.nextInt(); a inp.nextInt() inp.nextInt inp int b = inp.nextInt(); b inp.nextInt() inp.nextInt inp 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" Scanner inp inp
import java.util.*;

class Main {
    public static void main(String args[]) {
        Scanner inp = new Scanner(System.in);
        do_(inp);
        inp.close();
    }
    public static void do_(Scanner inp) {
        int k = inp.nextInt();
        int a = inp.nextInt();
        int b = inp.nextInt();
        for (int i = a; i <= b; i++) {
            if (i % k == 0) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
}
