My first is simply a vegetable, delicious, round and green.
My third and fourth are sound asleep, as plainly can be seen.
My fifth is fifty, clear enough for any riddle-setter.
Two of my second stacked on their sides will give my final letter.
Now that my second has my parts, fit them together well.
You see me now before your eyes; it's plain for all to tell.
What am I?
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