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();
      int C = 0;
      for(int i=A;i<B+1;i++){
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      }if(C>0){
        System.out.println("OK");
      }else{
        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();
      int C = 0;
      for(int i=A;i<B+1;i++){
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      }if(C>0){
        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 C = 0;
      for(int i=A;i<B+1;i++){
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      }if(C>0){
        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 C = 0;
      for(int i=A;i<B+1;i++){
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      }if(C>0){
        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 C = 0; C 0 for(int i=A;i<B+1;i++){
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      } int i=A; int i=A; i A i<B+1 i B+1 B 1 i++ i++ i {
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      } {
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      } if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        } i%K==0 i%K i K 0 {
          C=C+1;
          break;
        } C=C+1 C C+1 C 1 break; {
          continue;
        } continue; if(C>0){
        System.out.println("OK");
      }else{
        System.out.println("NG");
      } C>0 C 0 {
        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 C = 0;
      for(int i=A;i<B+1;i++){
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      }if(C>0){
        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 C = 0;
      for(int i=A;i<B+1;i++){
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      }if(C>0){
        System.out.println("OK");
      }else{
        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();
      int C = 0;
      for(int i=A;i<B+1;i++){
        if(i%K==0){
          C=C+1;
          break;
        }else{
          continue;
        }
      }if(C>0){
        System.out.println("OK");
      }else{
        System.out.println("NG");
      }
    }
}