import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	int K = sc.nextInt();
      	int A = sc.nextInt();
      	int B = sc.nextInt();
      	for(int i=A;i<=B;i++){
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("NG");
            }
        }
    }
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	int K = sc.nextInt();
      	int A = sc.nextInt();
      	int B = sc.nextInt();
      	for(int i=A;i<=B;i++){
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("NG");
            }
        }
    }
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	int K = sc.nextInt();
      	int A = sc.nextInt();
      	int B = sc.nextInt();
      	for(int i=A;i<=B;i++){
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("NG");
            }
        }
    } main {
		Scanner sc = new Scanner(System.in);
      	int K = sc.nextInt();
      	int A = sc.nextInt();
      	int B = sc.nextInt();
      	for(int i=A;i<=B;i++){
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("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 for(int i=A;i<=B;i++){
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("NG");
            }
        } int i=A; int i=A; i A i<=B i B i++ i++ i {
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("NG");
            }
        } {
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("NG");
            }
        } if(i%K==0){
            	System.out.println("OK");
              	break;
            } i%K==0 i%K i K 0 {
            	System.out.println("OK");
              	break;
            } System.out.println("OK") System.out.println System.out System System.out "OK" break; if(i==B && i%K!=0){
            	System.out.println("NG");
            } i==B && i%K!=0 i==B i B i%K!=0 i%K i K 0 {
            	System.out.println("NG");
            } 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){
		Scanner sc = new Scanner(System.in);
      	int K = sc.nextInt();
      	int A = sc.nextInt();
      	int B = sc.nextInt();
      	for(int i=A;i<=B;i++){
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("NG");
            }
        }
    }
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	int K = sc.nextInt();
      	int A = sc.nextInt();
      	int B = sc.nextInt();
      	for(int i=A;i<=B;i++){
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("NG");
            }
        }
    }
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
      	int K = sc.nextInt();
      	int A = sc.nextInt();
      	int B = sc.nextInt();
      	for(int i=A;i<=B;i++){
        	if(i%K==0){
            	System.out.println("OK");
              	break;
            }
          	if(i==B && i%K!=0){
            	System.out.println("NG");
            }
        }
    }
}