import java.util.Scanner;

/**
 * https://atcoder.jp/contests/abc165/tasks/abc165_a
 */

class Main {

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

        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();

        System.out.println(canCarry(k, a, b) ? "OK" : "NG");

        scanner.close();

    }

    public static boolean canCarry(int k, int a, int b) {
        if (a % k == 0 || b % k == 0) return true;

        int c = a + (k - (a % k));
        if (c <= b) return true;
        return false;
    }
} import java.util.Scanner; Scanner java.util class Main {

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

        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();

        System.out.println(canCarry(k, a, b) ? "OK" : "NG");

        scanner.close();

    }

    public static boolean canCarry(int k, int a, int b) {
        if (a % k == 0 || b % k == 0) return true;

        int c = a + (k - (a % k));
        if (c <= b) return true;
        return false;
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();

        System.out.println(canCarry(k, a, b) ? "OK" : "NG");

        scanner.close();

    } main {
        Scanner scanner = new Scanner(System.in);

        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();

        System.out.println(canCarry(k, a, b) ? "OK" : "NG");

        scanner.close();

    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int k = scanner.nextInt(); k scanner.nextInt() scanner.nextInt scanner int a = scanner.nextInt(); a scanner.nextInt() scanner.nextInt scanner int b = scanner.nextInt(); b scanner.nextInt() scanner.nextInt scanner System.out.println(canCarry(k, a, b) ? "OK" : "NG") System.out.println System.out System System.out canCarry(k, a, b) ? "OK" : "NG" canCarry(k, a, b) canCarry k a b "OK" "NG" scanner.close() scanner.close scanner String[] args args public static boolean canCarry(int k, int a, int b) {
        if (a % k == 0 || b % k == 0) return true;

        int c = a + (k - (a % k));
        if (c <= b) return true;
        return false;
    } canCarry {
        if (a % k == 0 || b % k == 0) return true;

        int c = a + (k - (a % k));
        if (c <= b) return true;
        return false;
    } if (a % k == 0 || b % k == 0) return true; a % k == 0 || b % k == 0 a % k == 0 a % k a k 0 b % k == 0 b % k b k 0 return true; true int c = a + (k - (a % k)); c a + (k - (a % k)) a (k - (a % k)) k (a % k) a k if (c <= b) return true; c <= b c b return true; true return false; false int k k int a a int b b
import java.util.Scanner;

/**
 * https://atcoder.jp/contests/abc165/tasks/abc165_a
 */

class Main {

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

        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();

        System.out.println(canCarry(k, a, b) ? "OK" : "NG");

        scanner.close();

    }

    public static boolean canCarry(int k, int a, int b) {
        if (a % k == 0 || b % k == 0) return true;

        int c = a + (k - (a % k));
        if (c <= b) return true;
        return false;
    }
}