import java.util.*;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		for(int i = b; i <= c; i++){
			if(i % a == 0){
				System.out.print("OK");
				return;
			}
		}
		System.out.print("NG");
	}
} import java.util.*; util.* java class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		for(int i = b; i <= c; i++){
			if(i % a == 0){
				System.out.print("OK");
				return;
			}
		}
		System.out.print("NG");
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		for(int i = b; i <= c; i++){
			if(i % a == 0){
				System.out.print("OK");
				return;
			}
		}
		System.out.print("NG");
	} main {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		for(int i = b; i <= c; i++){
			if(i % a == 0){
				System.out.print("OK");
				return;
			}
		}
		System.out.print("NG");
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int c = sc.nextInt(); c sc.nextInt() sc.nextInt sc for(int i = b; i <= c; i++){
			if(i % a == 0){
				System.out.print("OK");
				return;
			}
		} int i = b; int i = b; i b i <= c i c i++ i++ i {
			if(i % a == 0){
				System.out.print("OK");
				return;
			}
		} {
			if(i % a == 0){
				System.out.print("OK");
				return;
			}
		} if(i % a == 0){
				System.out.print("OK");
				return;
			} i % a == 0 i % a i a 0 {
				System.out.print("OK");
				return;
			} System.out.print("OK") System.out.print System.out System System.out "OK" return; System.out.print("NG") System.out.print System.out System System.out "NG" String[] args args
import java.util.*;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		for(int i = b; i <= c; i++){
			if(i % a == 0){
				System.out.print("OK");
				return;
			}
		}
		System.out.print("NG");
	}
}