#886. Function f(x) = -x² + 4x
Write a function `def f(x):` that returns f(x) = -x² + 4x. Print f(x) for the x given in the input.
### Input
One integer x (-100 ≤ x ≤ 100).
### Output
A number.
Examples
Input
-28
Output
-896
Input
89
Output
-7565
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.