


Time Limit:1000MS  Memory Limit:65536K

Description
εϵסµ׺͸ߣҪεܳ

Input
ֻһУÿγUDHֱʾεϵסµ׺͸ߡ 0 < U < D, 0 < H

Output
Уһεڶεܳܳ2λС

Sample Input
2 8 4

Sample Output
20.00
20.00

Source
Lin Jialiang@BNUEP
