import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        // input
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        String ans = "";
        int x = a / k;
        int y = b / k;
        int z = a % k;
        int w = b % k;
        if (y - x >= 1 || (z == 0 || w == 0)) ans = "OK";
        else ans = "NG";

        System.out.println(ans);
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        // input
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        String ans = "";
        int x = a / k;
        int y = b / k;
        int z = a % k;
        int w = b % k;
        if (y - x >= 1 || (z == 0 || w == 0)) ans = "OK";
        else ans = "NG";

        System.out.println(ans);
    }
} Main public static void main(String[] args) {
        // input
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        String ans = "";
        int x = a / k;
        int y = b / k;
        int z = a % k;
        int w = b % k;
        if (y - x >= 1 || (z == 0 || w == 0)) ans = "OK";
        else ans = "NG";

        System.out.println(ans);
    } main {
        // input
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        String ans = "";
        int x = a / k;
        int y = b / k;
        int z = a % k;
        int w = b % k;
        if (y - x >= 1 || (z == 0 || w == 0)) ans = "OK";
        else ans = "NG";

        System.out.println(ans);
    } 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 String ans = ""; ans "" int x = a / k; x a / k a k int y = b / k; y b / k b k int z = a % k; z a % k a k int w = b % k; w b % k b k if (y - x >= 1 || (z == 0 || w == 0)) ans = "OK";
        else ans = "NG"; y - x >= 1 || (z == 0 || w == 0) y - x >= 1 y - x y x 1 (z == 0 || w == 0) z == 0 z 0 w == 0 w 0 ans = "OK" ans "OK" ans = "NG" ans "NG" System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {

    public static void main(String[] args) {
        // input
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        String ans = "";
        int x = a / k;
        int y = b / k;
        int z = a % k;
        int w = b % k;
        if (y - x >= 1 || (z == 0 || w == 0)) ans = "OK";
        else ans = "NG";

        System.out.println(ans);
    }
} public class Main {

    public static void main(String[] args) {
        // input
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        String ans = "";
        int x = a / k;
        int y = b / k;
        int z = a % k;
        int w = b % k;
        if (y - x >= 1 || (z == 0 || w == 0)) ans = "OK";
        else ans = "NG";

        System.out.println(ans);
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        // input
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        String ans = "";
        int x = a / k;
        int y = b / k;
        int z = a % k;
        int w = b % k;
        if (y - x >= 1 || (z == 0 || w == 0)) ans = "OK";
        else ans = "NG";

        System.out.println(ans);
    }
}
