import java.util.Scanner;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int k = sc.nextInt();
		// スペース区切りの整数の入力
		int a = sc.nextInt();
		int b = sc.nextInt();
        int r = 0;
		// 判定
		for(int i = a; i <= b; i ++){
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		}
		if(r == 0){
            System.out.print("NG");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int k = sc.nextInt();
		// スペース区切りの整数の入力
		int a = sc.nextInt();
		int b = sc.nextInt();
        int r = 0;
		// 判定
		for(int i = a; i <= b; i ++){
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		}
		if(r == 0){
            System.out.print("NG");
		}
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int k = sc.nextInt();
		// スペース区切りの整数の入力
		int a = sc.nextInt();
		int b = sc.nextInt();
        int r = 0;
		// 判定
		for(int i = a; i <= b; i ++){
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		}
		if(r == 0){
            System.out.print("NG");
		}
	} main {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int k = sc.nextInt();
		// スペース区切りの整数の入力
		int a = sc.nextInt();
		int b = sc.nextInt();
        int r = 0;
		// 判定
		for(int i = a; i <= b; i ++){
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		}
		if(r == 0){
            System.out.print("NG");
		}
	} 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 int r = 0; r 0 for(int i = a; i <= b; i ++){
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		} int i = a; int i = a; i a i <= b i b i ++ i ++ i {
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		} {
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		} if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			} i % k == 0 i % k i k 0 {
				System.out.print("OK");
				r = 1;
				break;
			} System.out.print("OK") System.out.print System.out System System.out "OK" r = 1 r 1 break; if(r == 0){
            System.out.print("NG");
		} r == 0 r 0 {
            System.out.print("NG");
		} System.out.print("NG") System.out.print System.out System System.out "NG" String[] args args public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int k = sc.nextInt();
		// スペース区切りの整数の入力
		int a = sc.nextInt();
		int b = sc.nextInt();
        int r = 0;
		// 判定
		for(int i = a; i <= b; i ++){
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		}
		if(r == 0){
            System.out.print("NG");
		}
	}
} public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int k = sc.nextInt();
		// スペース区切りの整数の入力
		int a = sc.nextInt();
		int b = sc.nextInt();
        int r = 0;
		// 判定
		for(int i = a; i <= b; i ++){
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		}
		if(r == 0){
            System.out.print("NG");
		}
	}
} Main
import java.util.Scanner;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int k = sc.nextInt();
		// スペース区切りの整数の入力
		int a = sc.nextInt();
		int b = sc.nextInt();
        int r = 0;
		// 判定
		for(int i = a; i <= b; i ++){
			if(i % k == 0){
				System.out.print("OK");
				r = 1;
				break;
			}
		}
		if(r == 0){
            System.out.print("NG");
		}
	}
}