import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        final Scanner sc = new Scanner(System.in);

        final int k = sc.nextInt();
        final int a = sc.nextInt();
        final int b = sc.nextInt();

        for (int i = k; i <= b; i += k) {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        final Scanner sc = new Scanner(System.in);

        final int k = sc.nextInt();
        final int a = sc.nextInt();
        final int b = sc.nextInt();

        for (int i = k; i <= b; i += k) {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} Main public static void main(String[] args) {
        final Scanner sc = new Scanner(System.in);

        final int k = sc.nextInt();
        final int a = sc.nextInt();
        final int b = sc.nextInt();

        for (int i = k; i <= b; i += k) {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    } main {
        final Scanner sc = new Scanner(System.in);

        final int k = sc.nextInt();
        final int a = sc.nextInt();
        final int b = sc.nextInt();

        for (int i = k; i <= b; i += k) {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    } final Scanner sc = new Scanner(System.in); sc new Scanner(System.in) final int k = sc.nextInt(); k sc.nextInt() sc.nextInt sc final int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc final int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc for (int i = k; i <= b; i += k) {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        } int i = k; int i = k; i k i <= b i b i += k i += k i k {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        } {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        } if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            } a <= i && i <= b a <= i a i i <= b i b {
                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" String[] args args public class Main {

    public static void main(String[] args) {
        final Scanner sc = new Scanner(System.in);

        final int k = sc.nextInt();
        final int a = sc.nextInt();
        final int b = sc.nextInt();

        for (int i = k; i <= b; i += k) {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} public class Main {

    public static void main(String[] args) {
        final Scanner sc = new Scanner(System.in);

        final int k = sc.nextInt();
        final int a = sc.nextInt();
        final int b = sc.nextInt();

        for (int i = k; i <= b; i += k) {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        final Scanner sc = new Scanner(System.in);

        final int k = sc.nextInt();
        final int a = sc.nextInt();
        final int b = sc.nextInt();

        for (int i = k; i <= b; i += k) {
            if (a <= i && i <= b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
}
