The root of a cubic equation

Very easy

Execution time limit is 1 second

Runtime memory usage limit is 128 megabytes

Given a cubic equation

a x^{3} + b x^{2} + c x + d = 0 (a \neq = 0)

It is known that this equation has exactly one root. Find it.

Input

Four integers: $a, b, c, d (- 1000 \leq a, b, c, d \leq 1000)$ .

Print the root of equation with no less than **6** decimal digits.

Input #1

Answer #1

Input #2

Answer #2

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