Crossed Ladders

As shown in the figure below, a narrow alley runs between two tall buildings. A ladder of length x starts at the bottom of the right building and leans against the left building. A ladder of length y starts at the bottom of the left building and leans against the right building. The two ladders cross at a point exactly c above the ground. Find the width between the two buildings.

The first line contains three positive real numbers x, y, and c, in that order. Each number may be given with up to six digits after the decimal point and is at most 3,000,000,000.

Print the width between the two buildings. An absolute or relative error of at most 10^-3 is accepted.