import java.util.*;
class Main{
public static void main(String[]args){
Scanner sc=new Scanner(System.in);
  int n=sc.nextInt();
  int m=sc.nextInt();
  int k=sc.nextInt();
  System.out.println((k/n*n)>=m?"OK":"NG");
}
} import java.util.*; util.* java class Main{
public static void main(String[]args){
Scanner sc=new Scanner(System.in);
  int n=sc.nextInt();
  int m=sc.nextInt();
  int k=sc.nextInt();
  System.out.println((k/n*n)>=m?"OK":"NG");
}
} Main public static void main(String[]args){
Scanner sc=new Scanner(System.in);
  int n=sc.nextInt();
  int m=sc.nextInt();
  int k=sc.nextInt();
  System.out.println((k/n*n)>=m?"OK":"NG");
} main {
Scanner sc=new Scanner(System.in);
  int n=sc.nextInt();
  int m=sc.nextInt();
  int k=sc.nextInt();
  System.out.println((k/n*n)>=m?"OK":"NG");
} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int n=sc.nextInt(); n sc.nextInt() sc.nextInt sc int m=sc.nextInt(); m sc.nextInt() sc.nextInt sc int k=sc.nextInt(); k sc.nextInt() sc.nextInt sc System.out.println((k/n*n)>=m?"OK":"NG") System.out.println System.out System System.out (k/n*n)>=m?"OK":"NG" (k/n*n)>=m (k/n*n) k/n k n n m "OK" "NG" String[]args args
import java.util.*;
class Main{
public static void main(String[]args){
Scanner sc=new Scanner(System.in);
  int n=sc.nextInt();
  int m=sc.nextInt();
  int k=sc.nextInt();
  System.out.println((k/n*n)>=m?"OK":"NG");
}
}