\problemname{Howl}
\illustration{.4}{howl}{\href{https://pixabay.com/illustrations/wolf-howl-moon-weird-surreal-963081/}{Pixabay License, Alexas Fotos}}

\noindent
Returning to the Beautiful Gloomy Outback (BGO) after a strenuous trip to the city, you hear a faint howl in the distance. Instantly you realize it is your friend Fenrir inviting you to a howling contest.

In order to make an impressive howl that wins the contest, you know that your howl must fulfill the following criteria in order to be valid:
\begin{itemize}
    \item It must consist of a combination of the letters \texttt{A}, \texttt{H}, \texttt{O} and \texttt{W}. Each letter must occur at least once.
    \item The howl can not contain two consecutive \texttt{W}'s, or two consecutive \texttt{H}'s.
    \item The howl can not contain an \texttt{H} followed immediately by a \texttt{W} or an \texttt{A}.
    \item There can never be an \texttt{A} after the first occurrence of an \texttt{O}.
\end{itemize}
%
Can you produce a longer howl than Fenrir and win the contest?

\section*{Input}
The first and only line of input contains a single word, the howl of Fenrir. Since Fenrir is a proper wolf, his howls are always valid. Writing down Fenrir's howl will require at most $1$ MB of computer memory.

\section*{Output}
A valid howl which will win the howling contest.


%%% 
%%% O(n) solution: DP filled in backwards. Let j be a sliding pointer that
%%% is always pointing to the first entry not covered if a period ticket is
%%% bought at beginning of i'th trip (smallest j s.t tj >= ti + m).
%%% dp[i] is defined to be cheapest cost of travelling from trip i to future.
%%% dp[i] = min(dp[i+1] + s, dp[j] + p)
