import java.util.Scanner;

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

		// 入力値の取得
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();

		// 結果の出力
		System.out.println(B % K > B - A? "NG" : "OK");

		sc.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		// 入力値の取得
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();

		// 結果の出力
		System.out.println(B % K > B - A? "NG" : "OK");

		sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		// 入力値の取得
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();

		// 結果の出力
		System.out.println(B % K > B - A? "NG" : "OK");

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

		// 入力値の取得
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();

		// 結果の出力
		System.out.println(B % K > B - A? "NG" : "OK");

		sc.close();
	} 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 System.out.println(B % K > B - A? "NG" : "OK") System.out.println System.out System System.out B % K > B - A? "NG" : "OK" B % K > B - A B % K B K B - A B A "NG" "OK" sc.close() sc.close sc String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		// 入力値の取得
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();

		// 結果の出力
		System.out.println(B % K > B - A? "NG" : "OK");

		sc.close();
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		// 入力値の取得
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();

		// 結果の出力
		System.out.println(B % K > B - A? "NG" : "OK");

		sc.close();
	}
} Main
import java.util.Scanner;

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

		// 入力値の取得
		int K = sc.nextInt();
		int A = sc.nextInt();
		int B = sc.nextInt();

		// 結果の出力
		System.out.println(B % K > B - A? "NG" : "OK");

		sc.close();
	}
}
