A12851. Water Lily

While sailing on a boat, Inessa noticed a beautiful water lily flower above the lake's surface. She came closer and it turned out that the lily was exactly $H$ centimeters above the water surface. Inessa grabbed the flower and sailed the distance of $L$ centimeters. Exactly at this point the flower touched the water surface.

Suppose that the lily grows at some point $A$ on the lake bottom, and its stem is always a straight segment with one endpoint at point $A$ . Also suppose that initially the flower was exactly above the point $A$ , i.e. its stem was vertical. Can you determine the depth of the lake at point $A$ ?

The only line contains two integers $H$ and $L$ ( $1 \le H < L \le 10^{6}$ ).

Print a single number — the depth of the lake at point $A$ . The absolute or relative error should not exceed $10^{-6}$ .

Formally, let your answer be $A$ , and the jury's answer be $B$ . Your answer is accepted if and only if $\frac{|A - B|}{\max{(1, |B|)}} \le 10^{-6}$ .