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 x = ( a/k + 1 ) * k;
            
      if (x <= b || a % k == 0 || b % k == 0 || k == 1) {
         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 x = ( a/k + 1 ) * k;
            
      if (x <= b || a % k == 0 || b % k == 0 || k == 1) {
         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 x = ( a/k + 1 ) * k;
            
      if (x <= b || a % k == 0 || b % k == 0 || k == 1) {
         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 x = ( a/k + 1 ) * k;
            
      if (x <= b || a % k == 0 || b % k == 0 || k == 1) {
         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 x = ( a/k + 1 ) * k; x ( a/k + 1 ) * k ( a/k + 1 ) a/k a k 1 k if (x <= b || a % k == 0 || b % k == 0 || k == 1) {
         System.out.println("OK");
      } else {
         System.out.println("NG");
      } x <= b || a % k == 0 || b % k == 0 || k == 1 b % k == 0 x <= b || a % k == 0 || b % k == 0 || k == 1 x <= b x b a % k == 0 a % k a k 0 b % k == 0 b % k b k 0 k == 1 k 1 {
         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 x = ( a/k + 1 ) * k;
            
      if (x <= b || a % k == 0 || b % k == 0 || k == 1) {
         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 x = ( a/k + 1 ) * k;
            
      if (x <= b || a % k == 0 || b % k == 0 || k == 1) {
         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 x = ( a/k + 1 ) * k;
            
      if (x <= b || a % k == 0 || b % k == 0 || k == 1) {
         System.out.println("OK");
      } else {
         System.out.println("NG");
      }
   }
}
