B. Water Lily
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

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 $A$?

Input

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

Output

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 $\frac{|A - B|}{\max{(1, |B|)}} \le 10^{-6}$.

Examples
Input
1 2

Output
1.5000000000000

Input
3 5

Output
2.6666666666667