Barbos and Mukhtar
In a Great Clearing, there stood two Great Trees: a Great Oak and a Great Plane Tree. Two dogs were tied to the Great Oak: Barbos, with a chain length of x meters, and Mukhtar, with a chain length of y meters. One day, Barbos decided to move away from Mukhtar and ran as far as his chain would allow from the Great Oak. Mukhtar, inspired by Barbos, did the same and stretched his chain to its limit. They both ended up at the end of a Straight Path, where the Great Plane Tree was located. They realized that the distance from the Great Oak to the Great Plane Tree was the same as the distance from the Great Oak to the Straight Path. Moreover, Barbos noticed that he had to run z times farther along the Straight Path to reach the Great Plane Tree than Mukhtar did.
In the Great Clearing, all dogs understand that Great Trees are considered as points, and the Straight Path is a line segment.
Help Barbos and Mukhtar determine the distance from the Great Oak to the Great Plane Tree.
Input
Three real numbers x, y, z (0 < x, y, z < 10^7).
Output
Print the distance from the Great Oak to the Great Plane Tree with 9 decimal places. If this distance cannot be determined, print the word IMPOSSIBLE.