Problem Description

Sven Cal Payang is a Natural who was a member of the Phantom Pain Special Forces and piloted the GAT-X105E Strike Noir.
As is known, Sven was astronomy amateur when he was still a child. After the war between ZAFT and Earth Alliance, he decided to continue his childhood dream.
Sven’s new house is located at a peaceful town. What’s more, there is a lake in his garden. One day, he came up with a new idea on finding stars using interference phenomenon. He put a radio wave receiver h meter above the surface of a lake. When a radio star rising, it detects maxima successively due to interference of radio waves from the star, and its reflection waves from the water. The wavelength of the waves is λ centimeters. Sven wants to find stars as quickly as possible. Can you help him?

Input

Several cases are given until the end of input. Each line contains h and λ separated by a space.

Output

Print the minimum altitude angle of the star in degree. The value should be accurate to two decimal points. (There may be several result for one case, but only output the minimum altitude angle!)

0.5 20.0
20.0 0.5

5.74
0.00

Hint

Notice: When light reflected from a medium having an index of refraction greater than that of the medium in which it is traveling, a 180°phase change (or λ/2 shift )
occurs.