import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int K, A, B;
        Scanner sc = new Scanner(System.in);
        K = sc.nextInt();
        A = sc.nextInt();
        B = sc.nextInt();
        int temp = B/K;
        if(temp*K >= A)
        System.out.println("OK");
        else System.out.println("NG");
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        int K, A, B;
        Scanner sc = new Scanner(System.in);
        K = sc.nextInt();
        A = sc.nextInt();
        B = sc.nextInt();
        int temp = B/K;
        if(temp*K >= A)
        System.out.println("OK");
        else System.out.println("NG");
    }
} Main public static void main(String[] args) {
        int K, A, B;
        Scanner sc = new Scanner(System.in);
        K = sc.nextInt();
        A = sc.nextInt();
        B = sc.nextInt();
        int temp = B/K;
        if(temp*K >= A)
        System.out.println("OK");
        else System.out.println("NG");
    } main {
        int K, A, B;
        Scanner sc = new Scanner(System.in);
        K = sc.nextInt();
        A = sc.nextInt();
        B = sc.nextInt();
        int temp = B/K;
        if(temp*K >= A)
        System.out.println("OK");
        else System.out.println("NG");
    } int K K A A B; B Scanner sc = new Scanner(System.in); sc new Scanner(System.in) K = sc.nextInt() K sc.nextInt() sc.nextInt sc A = sc.nextInt() A sc.nextInt() sc.nextInt sc B = sc.nextInt() B sc.nextInt() sc.nextInt sc int temp = B/K; temp B/K B K if(temp*K >= A)
        System.out.println("OK");
        else System.out.println("NG"); temp*K >= A temp*K temp K A System.out.println("OK") System.out.println System.out System System.out "OK" 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) {
        int K, A, B;
        Scanner sc = new Scanner(System.in);
        K = sc.nextInt();
        A = sc.nextInt();
        B = sc.nextInt();
        int temp = B/K;
        if(temp*K >= A)
        System.out.println("OK");
        else System.out.println("NG");
    }
} public class Main {
    public static void main(String[] args) {
        int K, A, B;
        Scanner sc = new Scanner(System.in);
        K = sc.nextInt();
        A = sc.nextInt();
        B = sc.nextInt();
        int temp = B/K;
        if(temp*K >= A)
        System.out.println("OK");
        else System.out.println("NG");
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int K, A, B;
        Scanner sc = new Scanner(System.in);
        K = sc.nextInt();
        A = sc.nextInt();
        B = sc.nextInt();
        int temp = B/K;
        if(temp*K >= A)
        System.out.println("OK");
        else System.out.println("NG");
    }
}
