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();
    String ans = (a/k * k + k <= b || a%k == 0) ? "OK" : "NG";
    System.out.println(ans);
  }
} 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();
    String ans = (a/k * k + k <= b || a%k == 0) ? "OK" : "NG";
    System.out.println(ans);
  }
} 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();
    String ans = (a/k * k + k <= b || a%k == 0) ? "OK" : "NG";
    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);
    int k = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    String ans = (a/k * k + k <= b || a%k == 0) ? "OK" : "NG";
    System.out.println(ans);
  } 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 String ans = (a/k * k + k <= b || a%k == 0) ? "OK" : "NG"; ans (a/k * k + k <= b || a%k == 0) ? "OK" : "NG" (a/k * k + k <= b || a%k == 0) a/k * k + k <= b a/k * k + k a/k * k a/k a k k k b a%k == 0 a%k a k 0 "OK" "NG" System.out.println(ans) System.out.println System.out System System.out ans 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();
    String ans = (a/k * k + k <= b || a%k == 0) ? "OK" : "NG";
    System.out.println(ans);
  }
} 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();
    String ans = (a/k * k + k <= b || a%k == 0) ? "OK" : "NG";
    System.out.println(ans);
  }
} 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();
    String ans = (a/k * k + k <= b || a%k == 0) ? "OK" : "NG";
    System.out.println(ans);
  }
}