import java.io.*;
import java.util.*;
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 n=1;
    while(n<=(B/K))
    {
      if(A<=(K*n) && (K*n)<=B)
      {
        System.out.print("OK");
        return;
      }
      else
      n++;
    }
    System.out.print("NG");
  }
} import java.io.*; io.* java import java.util.*; util.* java 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 n=1;
    while(n<=(B/K))
    {
      if(A<=(K*n) && (K*n)<=B)
      {
        System.out.print("OK");
        return;
      }
      else
      n++;
    }
    System.out.print("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 n=1;
    while(n<=(B/K))
    {
      if(A<=(K*n) && (K*n)<=B)
      {
        System.out.print("OK");
        return;
      }
      else
      n++;
    }
    System.out.print("NG");
  } main {
   Scanner sc=new Scanner(System.in);
    int K=sc.nextInt();
    int A=sc.nextInt();
    int B=sc.nextInt();
    int n=1;
    while(n<=(B/K))
    {
      if(A<=(K*n) && (K*n)<=B)
      {
        System.out.print("OK");
        return;
      }
      else
      n++;
    }
    System.out.print("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 n=1; n 1 while(n<=(B/K))
    {
      if(A<=(K*n) && (K*n)<=B)
      {
        System.out.print("OK");
        return;
      }
      else
      n++;
    } n<=(B/K) n (B/K) B K {
      if(A<=(K*n) && (K*n)<=B)
      {
        System.out.print("OK");
        return;
      }
      else
      n++;
    } if(A<=(K*n) && (K*n)<=B)
      {
        System.out.print("OK");
        return;
      }
      else
      n++; A<=(K*n) && (K*n)<=B A<=(K*n) A (K*n) K n (K*n)<=B (K*n) K n B {
        System.out.print("OK");
        return;
      } System.out.print("OK") System.out.print System.out System System.out "OK" return; n++ n System.out.print("NG") System.out.print System.out System System.out "NG" String [] args args
import java.io.*;
import java.util.*;
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 n=1;
    while(n<=(B/K))
    {
      if(A<=(K*n) && (K*n)<=B)
      {
        System.out.print("OK");
        return;
      }
      else
      n++;
    }
    System.out.print("NG");
  }
}