import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        try (Scanner s = new Scanner(System.in)) {
            int k = s.nextInt();
            int a = s.nextInt();
            int b = s.nextInt();
            int mod = a % k;
            int d = b - a;
            System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG");
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        try (Scanner s = new Scanner(System.in)) {
            int k = s.nextInt();
            int a = s.nextInt();
            int b = s.nextInt();
            int mod = a % k;
            int d = b - a;
            System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG");
        }
    }
} Main public static void main(String[] args) throws Exception {
        try (Scanner s = new Scanner(System.in)) {
            int k = s.nextInt();
            int a = s.nextInt();
            int b = s.nextInt();
            int mod = a % k;
            int d = b - a;
            System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG");
        }
    } main {
        try (Scanner s = new Scanner(System.in)) {
            int k = s.nextInt();
            int a = s.nextInt();
            int b = s.nextInt();
            int mod = a % k;
            int d = b - a;
            System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG");
        }
    } try (Scanner s = new Scanner(System.in)) {
            int k = s.nextInt();
            int a = s.nextInt();
            int b = s.nextInt();
            int mod = a % k;
            int d = b - a;
            System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG");
        } {
            int k = s.nextInt();
            int a = s.nextInt();
            int b = s.nextInt();
            int mod = a % k;
            int d = b - a;
            System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG");
        } Scanner s = new Scanner(System.in) Scanner s = new Scanner(System.in) new Scanner(System.in) int k = s.nextInt(); k s.nextInt() s.nextInt s int a = s.nextInt(); a s.nextInt() s.nextInt s int b = s.nextInt(); b s.nextInt() s.nextInt s int mod = a % k; mod a % k a k int d = b - a; d b - a b a System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG") System.out.println System.out System System.out (mod == 0 || (k - mod) <= d) ? "OK" : "NG" (mod == 0 || (k - mod) <= d) mod == 0 mod 0 (k - mod) <= d (k - mod) k mod d "OK" "NG" String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        try (Scanner s = new Scanner(System.in)) {
            int k = s.nextInt();
            int a = s.nextInt();
            int b = s.nextInt();
            int mod = a % k;
            int d = b - a;
            System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG");
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        try (Scanner s = new Scanner(System.in)) {
            int k = s.nextInt();
            int a = s.nextInt();
            int b = s.nextInt();
            int mod = a % k;
            int d = b - a;
            System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG");
        }
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        try (Scanner s = new Scanner(System.in)) {
            int k = s.nextInt();
            int a = s.nextInt();
            int b = s.nextInt();
            int mod = a % k;
            int d = b - a;
            System.out.println((mod == 0 || (k - mod) <= d) ? "OK" : "NG");
        }
    }
}
