In a frenzied effort to avoid 5m, and neither hand looking ideal for 3NT, you stumble into 4♠ by S. The auction is not a thing of beauty.
LHO cashes the ♣A at trick 1, then switches to a heart. What's the best line here, given that (a) it's matchpoints and (b) the field will probably be in a diamond contract, half of them in partscore?