import java.util.Scanner;
 
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();
      
      int B1 =(B/K)*K;
      
      if(A<=B1){
        System.out.println("OK");
      }
      else{
        System.out.println("NG");
      }
    }
} import java.util.Scanner; Scanner 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();
      
      int B1 =(B/K)*K;
      
      if(A<=B1){
        System.out.println("OK");
      }
      else{
        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();
      
      int B1 =(B/K)*K;
      
      if(A<=B1){
        System.out.println("OK");
      }
      else{
        System.out.println("NG");
      }
    } main {
      Scanner sc = new Scanner(System.in);
      int K = sc.nextInt();
      int A = sc.nextInt();
      int B = sc.nextInt();
      
      int B1 =(B/K)*K;
      
      if(A<=B1){
        System.out.println("OK");
      }
      else{
        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 int B1 =(B/K)*K; B1 (B/K)*K (B/K) B K K if(A<=B1){
        System.out.println("OK");
      }
      else{
        System.out.println("NG");
      } A<=B1 A B1 {
        System.out.println("OK");
      } System.out.println("OK") System.out.println System.out System System.out "OK" {
        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();
      
      int B1 =(B/K)*K;
      
      if(A<=B1){
        System.out.println("OK");
      }
      else{
        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();
      
      int B1 =(B/K)*K;
      
      if(A<=B1){
        System.out.println("OK");
      }
      else{
        System.out.println("NG");
      }
    }
} Main
import java.util.Scanner;
 
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();
      
      int B1 =(B/K)*K;
      
      if(A<=B1){
        System.out.println("OK");
      }
      else{
        System.out.println("NG");
      }
    }
}