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

    }
    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 n = sc.nextInt();
    int a= sc.nextInt();
    int b= sc.nextInt();
    boolean c = true;
    for(int i=a;i<=b;i++)
    {
      if(i%n==0)
      {System.out.println("OK");
     return;}

    }
    System.out.println("NG");
 
  }
} Main public static void main(String args[])
  {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int a= sc.nextInt();
    int b= sc.nextInt();
    boolean c = true;
    for(int i=a;i<=b;i++)
    {
      if(i%n==0)
      {System.out.println("OK");
     return;}

    }
    System.out.println("NG");
 
  } main {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int a= sc.nextInt();
    int b= sc.nextInt();
    boolean c = true;
    for(int i=a;i<=b;i++)
    {
      if(i%n==0)
      {System.out.println("OK");
     return;}

    }
    System.out.println("NG");
 
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n 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 boolean c = true; c true for(int i=a;i<=b;i++)
    {
      if(i%n==0)
      {System.out.println("OK");
     return;}

    } int i=a; int i=a; i a i<=b i b i++ i++ i {
      if(i%n==0)
      {System.out.println("OK");
     return;}

    } {
      if(i%n==0)
      {System.out.println("OK");
     return;}

    } if(i%n==0)
      {System.out.println("OK");
     return;} i%n==0 i%n i n 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 args[] args public class Main
{
  public static void main(String args[])
  {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int a= sc.nextInt();
    int b= sc.nextInt();
    boolean c = true;
    for(int i=a;i<=b;i++)
    {
      if(i%n==0)
      {System.out.println("OK");
     return;}

    }
    System.out.println("NG");
 
  }
} public class Main
{
  public static void main(String args[])
  {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int a= sc.nextInt();
    int b= sc.nextInt();
    boolean c = true;
    for(int i=a;i<=b;i++)
    {
      if(i%n==0)
      {System.out.println("OK");
     return;}

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

    }
    System.out.println("NG");
 
  }
}

        