import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.Collection;
import java.util.Scanner;
import java.util.Arrays;
import java.util.*;
class  Main{
  public   static  void main(String[]args){
Scanner in =new Scanner(System.in);
int k=in.nextInt();
int a=in.nextInt();
int b=in.nextInt();
int l=(b/k)*k;
if (a<=l) {
  System.out.print("OK ");
} else System.out.print("NG");}} import java.lang.reflect.Array; Array java.lang.reflect import java.math.BigInteger; BigInteger java.math import java.util.Collection; Collection java.util import java.util.Scanner; Scanner java.util import java.util.Arrays; Arrays java.util import java.util.*; util.* java class  Main{
  public   static  void main(String[]args){
Scanner in =new Scanner(System.in);
int k=in.nextInt();
int a=in.nextInt();
int b=in.nextInt();
int l=(b/k)*k;
if (a<=l) {
  System.out.print("OK ");
} else System.out.print("NG");}} Main public   static  void main(String[]args){
Scanner in =new Scanner(System.in);
int k=in.nextInt();
int a=in.nextInt();
int b=in.nextInt();
int l=(b/k)*k;
if (a<=l) {
  System.out.print("OK ");
} else System.out.print("NG");} main {
Scanner in =new Scanner(System.in);
int k=in.nextInt();
int a=in.nextInt();
int b=in.nextInt();
int l=(b/k)*k;
if (a<=l) {
  System.out.print("OK ");
} else System.out.print("NG");} Scanner in =new Scanner(System.in); in new Scanner(System.in) int k=in.nextInt(); k in.nextInt() in.nextInt in int a=in.nextInt(); a in.nextInt() in.nextInt in int b=in.nextInt(); b in.nextInt() in.nextInt in int l=(b/k)*k; l (b/k)*k (b/k) b k k if (a<=l) {
  System.out.print("OK ");
} else System.out.print("NG"); a<=l a l {
  System.out.print("OK ");
} System.out.print("OK ") System.out.print System.out System System.out "OK " System.out.print("NG") System.out.print System.out System System.out "NG" String[]args args
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.Collection;
import java.util.Scanner;
import java.util.Arrays;
import java.util.*;
class  Main{
  public   static  void main(String[]args){
Scanner in =new Scanner(System.in);
int k=in.nextInt();
int a=in.nextInt();
int b=in.nextInt();
int l=(b/k)*k;
if (a<=l) {
  System.out.print("OK ");
} else System.out.print("NG");}}