Tsumego From Games 12

Position at move 217  

DaveSigaty: From a game I just played. After killing the upper left, White's big dragon has managed to wander all over the right side without noticing that Black has slowly reduced it to only one eye (fairly typical I might say :-) The two marked stones have just been exchanged and White is set for a classic tsumego finish. How does he survive here?

/Solution