The water tank at Jack's house has two faucets. If only the first faucet is open, it takes ~a~ hours to fill the tank. If only the second faucet is open, it takes ~b~ hours to fill the tank. Jack wants to know how long it will take to fill the tank if both faucets are open simultaneously.

Input:

• A single line containing two positive integers ~a~ and ~b~ (~ a, b \leq 10^5 ~).

Output:

• Print a single line containing a real number with an accuracy of ~10^{-5}~ representing the time required to fill the tank with both faucets open.

Sample Input

4 5

Sample Output

2.22222