import java.util.Scanner;

public class Main{
 public static void main(String[] args) {
   Scanner kbd =new Scanner(System.in);
   int k=kbd.nextInt();
   int a=kbd.nextInt();
   int b=kbd.nextInt();
   int x=1;
 for(int i=1;i<=1000;i++){
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 }
  if(x==1){System.out.println("NG");
}}
 } import java.util.Scanner; Scanner java.util public class Main{
 public static void main(String[] args) {
   Scanner kbd =new Scanner(System.in);
   int k=kbd.nextInt();
   int a=kbd.nextInt();
   int b=kbd.nextInt();
   int x=1;
 for(int i=1;i<=1000;i++){
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 }
  if(x==1){System.out.println("NG");
}}
 } Main public static void main(String[] args) {
   Scanner kbd =new Scanner(System.in);
   int k=kbd.nextInt();
   int a=kbd.nextInt();
   int b=kbd.nextInt();
   int x=1;
 for(int i=1;i<=1000;i++){
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 }
  if(x==1){System.out.println("NG");
}} main {
   Scanner kbd =new Scanner(System.in);
   int k=kbd.nextInt();
   int a=kbd.nextInt();
   int b=kbd.nextInt();
   int x=1;
 for(int i=1;i<=1000;i++){
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 }
  if(x==1){System.out.println("NG");
}} Scanner kbd =new Scanner(System.in); kbd new Scanner(System.in) int k=kbd.nextInt(); k kbd.nextInt() kbd.nextInt kbd int a=kbd.nextInt(); a kbd.nextInt() kbd.nextInt kbd int b=kbd.nextInt(); b kbd.nextInt() kbd.nextInt kbd int x=1; x 1 for(int i=1;i<=1000;i++){
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 } int i=1; int i=1; i 1 i<=1000 i 1000 i++ i++ i {
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 } {
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 } if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   } a<=k*i&&k*i<=b a<=k*i a k*i k i k*i<=b k*i k i b {
     System.out.println("OK");
      x=0;
     break;
   } System.out.println("OK") System.out.println System.out System System.out "OK" x=0 x 0 break; if(x==1){System.out.println("NG");
} x==1 x 1 {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 kbd =new Scanner(System.in);
   int k=kbd.nextInt();
   int a=kbd.nextInt();
   int b=kbd.nextInt();
   int x=1;
 for(int i=1;i<=1000;i++){
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 }
  if(x==1){System.out.println("NG");
}}
 } public class Main{
 public static void main(String[] args) {
   Scanner kbd =new Scanner(System.in);
   int k=kbd.nextInt();
   int a=kbd.nextInt();
   int b=kbd.nextInt();
   int x=1;
 for(int i=1;i<=1000;i++){
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 }
  if(x==1){System.out.println("NG");
}}
 } Main
import java.util.Scanner;

public class Main{
 public static void main(String[] args) {
   Scanner kbd =new Scanner(System.in);
   int k=kbd.nextInt();
   int a=kbd.nextInt();
   int b=kbd.nextInt();
   int x=1;
 for(int i=1;i<=1000;i++){
   if(a<=k*i&&k*i<=b){
     System.out.println("OK");
      x=0;
     break;
   }
 }
  if(x==1){System.out.println("NG");
}}
 }
