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();
    
    while(b % k != 0){
      b = b - 1;
    }
    
    if(b < a){
      System.out.println("NG");
    }else{
      System.out.println("OK");
    }
    sc.close();
  }
} 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();
    
    while(b % k != 0){
      b = b - 1;
    }
    
    if(b < a){
      System.out.println("NG");
    }else{
      System.out.println("OK");
    }
    sc.close();
  }
} 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();
    
    while(b % k != 0){
      b = b - 1;
    }
    
    if(b < a){
      System.out.println("NG");
    }else{
      System.out.println("OK");
    }
    sc.close();
  } main {
    Scanner sc = new Scanner(System.in);
    int k = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    
    while(b % k != 0){
      b = b - 1;
    }
    
    if(b < a){
      System.out.println("NG");
    }else{
      System.out.println("OK");
    }
    sc.close();
  } 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 while(b % k != 0){
      b = b - 1;
    } b % k != 0 b % k b k 0 {
      b = b - 1;
    } b = b - 1 b b - 1 b 1 if(b < a){
      System.out.println("NG");
    }else{
      System.out.println("OK");
    } b < a b a {
      System.out.println("NG");
    } System.out.println("NG") System.out.println System.out System System.out "NG" {
      System.out.println("OK");
    } System.out.println("OK") System.out.println System.out System System.out "OK" sc.close() sc.close sc String args[] args
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();
    
    while(b % k != 0){
      b = b - 1;
    }
    
    if(b < a){
      System.out.println("NG");
    }else{
      System.out.println("OK");
    }
    sc.close();
  }
}