import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int m=sc.nextInt();
    int a=sc.nextInt();
    int b=sc.nextInt();
    if(a<=b){
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      }
    }
  }
} import java.util.Scanner; Scanner java.util public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int m=sc.nextInt();
    int a=sc.nextInt();
    int b=sc.nextInt();
    if(a<=b){
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      }
    }
  }
} Main public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int m=sc.nextInt();
    int a=sc.nextInt();
    int b=sc.nextInt();
    if(a<=b){
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      }
    }
  } main {
    Scanner sc=new Scanner(System.in);
    int m=sc.nextInt();
    int a=sc.nextInt();
    int b=sc.nextInt();
    if(a<=b){
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      }
    }
  } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int m=sc.nextInt(); m 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 if(a<=b){
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      }
    } a<=b a b {
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      }
    } for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      } int s=a; int s=a; s a s<=b s b s++ s++ s {
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      } {
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      } if(s%m==0){
          System.out.println("OK");
          break;
        } s%m==0 s%m s m 0 {
          System.out.println("OK");
          break;
        } System.out.println("OK") System.out.println System.out System System.out "OK" break; if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        } (s==b)&&!(b%m==0) (s==b) s b !(b%m==0) (b%m==0) b%m b m 0 {
          System.out.println("NG");
        } System.out.println("NG") System.out.println 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 m=sc.nextInt();
    int a=sc.nextInt();
    int b=sc.nextInt();
    if(a<=b){
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      }
    }
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int m=sc.nextInt();
    int a=sc.nextInt();
    int b=sc.nextInt();
    if(a<=b){
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      }
    }
  }
} Main
import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int m=sc.nextInt();
    int a=sc.nextInt();
    int b=sc.nextInt();
    if(a<=b){
      for(int s=a;s<=b;s++){
        if(s%m==0){
          System.out.println("OK");
          break;
        }
        if((s==b)&&!(b%m==0)){
          System.out.println("NG");
        }
      }
    }
  }
}
