Fifteen Puzzle

Shuffle the squares first then re-arrage the fifteen squares by repeatedly making moves that slide squares into the empty space.
How quickly can you solve it?

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    	American puzzle author and mathematician Sam Loyd is often falsely
    	credited with creating the puzzle; indeed, Loyd claimed from 1891
    	until his death in 1911 that he invented it.
    	The puzzle was actually created around 1874 by Noyes Palmer Chapman,
    	a postmaster in Canastota, New York.

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