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