CF924B Three-level Laser

An atom of element X can exist in $ n $ distinct states with energies $ E_{1}

The first line contains two integers $ n $ and $ U $ ( $ 3

If it is not possible to choose three states that satisfy all constraints, print -1. Otherwise, print one real number $ η $ — the maximum possible energy conversion efficiency. Your answer is considered correct its absolute or relative error does not exceed $ 10^{-9} $ . Formally, let your answer be $ a $ , and the jury's answer be $ b $ . Your answer is considered correct if .

In the first example choose states $ 1 $ , $ 2 $ and $ 3 $ , so that the energy conversion efficiency becomes equal to . In the second example choose states $ 4 $ , $ 5 $ and $ 9 $ , so that the energy conversion efficiency becomes equal to .