import java.io.PrintWriter;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        PrintWriter printWriter = new PrintWriter(System.out);
        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        for (int i = a; i < b + 1; i++){
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        }
        printWriter.println("NG");
        printWriter.flush();
    }
} import java.io.PrintWriter; PrintWriter java.io import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        PrintWriter printWriter = new PrintWriter(System.out);
        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        for (int i = a; i < b + 1; i++){
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        }
        printWriter.println("NG");
        printWriter.flush();
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        PrintWriter printWriter = new PrintWriter(System.out);
        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        for (int i = a; i < b + 1; i++){
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        }
        printWriter.println("NG");
        printWriter.flush();
    } main {
        Scanner scanner = new Scanner(System.in);
        PrintWriter printWriter = new PrintWriter(System.out);
        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        for (int i = a; i < b + 1; i++){
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        }
        printWriter.println("NG");
        printWriter.flush();
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) PrintWriter printWriter = new PrintWriter(System.out); printWriter new PrintWriter(System.out) 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 for (int i = a; i < b + 1; i++){
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        } int i = a; int i = a; i a i < b + 1 i b + 1 b 1 i++ i++ i {
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        } {
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        } if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            } i % k == 0 i % k i k 0 {
                printWriter.println("OK");
                printWriter.flush();
                return;
            } printWriter.println("OK") printWriter.println printWriter "OK" printWriter.flush() printWriter.flush printWriter return; printWriter.println("NG") printWriter.println printWriter "NG" printWriter.flush() printWriter.flush printWriter String[] args args public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        PrintWriter printWriter = new PrintWriter(System.out);
        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        for (int i = a; i < b + 1; i++){
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        }
        printWriter.println("NG");
        printWriter.flush();
    }
} public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        PrintWriter printWriter = new PrintWriter(System.out);
        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        for (int i = a; i < b + 1; i++){
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        }
        printWriter.println("NG");
        printWriter.flush();
    }
} Main
import java.io.PrintWriter;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        PrintWriter printWriter = new PrintWriter(System.out);
        int k = scanner.nextInt();
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        for (int i = a; i < b + 1; i++){
            if (i % k == 0) {
                printWriter.println("OK");
                printWriter.flush();
                return;
            }
        }
        printWriter.println("NG");
        printWriter.flush();
    }
}
