import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int judge=0, k=sc.nextInt(), a=sc.nextInt(), b=sc.nextInt();
    for(int i=a; i<=b; i++){
      if(i%k==0){
        judge=1;
        break;
      }
    }
    if(judge==1) System.out.print("OK");
    else System.out.print("NG");
  }
} import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int judge=0, k=sc.nextInt(), a=sc.nextInt(), b=sc.nextInt();
    for(int i=a; i<=b; i++){
      if(i%k==0){
        judge=1;
        break;
      }
    }
    if(judge==1) System.out.print("OK");
    else System.out.print("NG");
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int judge=0, k=sc.nextInt(), a=sc.nextInt(), b=sc.nextInt();
    for(int i=a; i<=b; i++){
      if(i%k==0){
        judge=1;
        break;
      }
    }
    if(judge==1) System.out.print("OK");
    else System.out.print("NG");
  } main {
    Scanner sc = new Scanner(System.in);
    int judge=0, k=sc.nextInt(), a=sc.nextInt(), b=sc.nextInt();
    for(int i=a; i<=b; i++){
      if(i%k==0){
        judge=1;
        break;
      }
    }
    if(judge==1) System.out.print("OK");
    else System.out.print("NG");
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int judge=0 judge 0 k=sc.nextInt() k sc.nextInt() sc.nextInt sc a=sc.nextInt() a sc.nextInt() sc.nextInt sc b=sc.nextInt(); b sc.nextInt() sc.nextInt sc for(int i=a; i<=b; i++){
      if(i%k==0){
        judge=1;
        break;
      }
    } int i=a; int i=a; i a i<=b i b i++ i++ i {
      if(i%k==0){
        judge=1;
        break;
      }
    } {
      if(i%k==0){
        judge=1;
        break;
      }
    } if(i%k==0){
        judge=1;
        break;
      } i%k==0 i%k i k 0 {
        judge=1;
        break;
      } judge=1 judge 1 break; if(judge==1) System.out.print("OK");
    else System.out.print("NG"); judge==1 judge 1 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 public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int judge=0, k=sc.nextInt(), a=sc.nextInt(), b=sc.nextInt();
    for(int i=a; i<=b; i++){
      if(i%k==0){
        judge=1;
        break;
      }
    }
    if(judge==1) System.out.print("OK");
    else System.out.print("NG");
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int judge=0, k=sc.nextInt(), a=sc.nextInt(), b=sc.nextInt();
    for(int i=a; i<=b; i++){
      if(i%k==0){
        judge=1;
        break;
      }
    }
    if(judge==1) System.out.print("OK");
    else System.out.print("NG");
  }
} Main
import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int judge=0, k=sc.nextInt(), a=sc.nextInt(), b=sc.nextInt();
    for(int i=a; i<=b; i++){
      if(i%k==0){
        judge=1;
        break;
      }
    }
    if(judge==1) System.out.print("OK");
    else System.out.print("NG");
  }
}