Ignoring the air resistance, velocity of a freely falling object $v$ after $t$ seconds and its drop $y$ in $t$ seconds are represented by the following formulas:
$ v = 9.8 t $
$ y = 4.9 t^2 $
A person is trying to drop down a glass ball and check whether it will crack. Your task is to write a program to help this experiment.
You are given the minimum velocity to crack the ball. Your program should print the lowest possible floor of a building to crack the ball. The height of the $N$ floor of the building is defined by $5 \times N - 5$.
The input consists of multiple datasets. Each dataset, a line, consists of the minimum velocity to crack the ball. The input ends with EOF. The number of datasets is less than or equal to 50.
For each dataset, print the lowest possible floor where the ball cracks.