import java.util.Scanner;
public class Main{
  public static void main (String args[]){
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    System.out.print(Logic.run(x,a,b));
  }
}
class Logic{
  public static String run(int x,int a,int b){
    String resMes="";
    for ( int i = a; i<=b;i++){
      if ( i%x == 0 ){
        resMes="OK";
        break;
      }
    }
    if (resMes.equals("")){
      resMes = "NG";
    }
    return resMes;
  }
} import java.util.Scanner; Scanner java.util public class Main{
  public static void main (String args[]){
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    System.out.print(Logic.run(x,a,b));
  }
} Main public static void main (String args[]){
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    System.out.print(Logic.run(x,a,b));
  } main {
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    System.out.print(Logic.run(x,a,b));
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int x = sc.nextInt(); x 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 System.out.print(Logic.run(x,a,b)) System.out.print System.out System System.out Logic.run(x,a,b) Logic.run Logic x a b String args[] args class Logic{
  public static String run(int x,int a,int b){
    String resMes="";
    for ( int i = a; i<=b;i++){
      if ( i%x == 0 ){
        resMes="OK";
        break;
      }
    }
    if (resMes.equals("")){
      resMes = "NG";
    }
    return resMes;
  }
} Logic public static String run(int x,int a,int b){
    String resMes="";
    for ( int i = a; i<=b;i++){
      if ( i%x == 0 ){
        resMes="OK";
        break;
      }
    }
    if (resMes.equals("")){
      resMes = "NG";
    }
    return resMes;
  } run {
    String resMes="";
    for ( int i = a; i<=b;i++){
      if ( i%x == 0 ){
        resMes="OK";
        break;
      }
    }
    if (resMes.equals("")){
      resMes = "NG";
    }
    return resMes;
  } String resMes=""; resMes "" for ( int i = a; i<=b;i++){
      if ( i%x == 0 ){
        resMes="OK";
        break;
      }
    } int i = a; int i = a; i a i<=b i b i++ i++ i {
      if ( i%x == 0 ){
        resMes="OK";
        break;
      }
    } {
      if ( i%x == 0 ){
        resMes="OK";
        break;
      }
    } if ( i%x == 0 ){
        resMes="OK";
        break;
      } i%x == 0 i%x i x 0 {
        resMes="OK";
        break;
      } resMes="OK" resMes "OK" break; if (resMes.equals("")){
      resMes = "NG";
    } resMes.equals("") resMes.equals resMes "" {
      resMes = "NG";
    } resMes = "NG" resMes "NG" return resMes; resMes int x x int a a int b b public class Main{
  public static void main (String args[]){
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    System.out.print(Logic.run(x,a,b));
  }
} public class Main{
  public static void main (String args[]){
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    System.out.print(Logic.run(x,a,b));
  }
} Main
import java.util.Scanner;
public class Main{
  public static void main (String args[]){
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    System.out.print(Logic.run(x,a,b));
  }
}
class Logic{
  public static String run(int x,int a,int b){
    String resMes="";
    for ( int i = a; i<=b;i++){
      if ( i%x == 0 ){
        resMes="OK";
        break;
      }
    }
    if (resMes.equals("")){
      resMes = "NG";
    }
    return resMes;
  }
}