# Physical Experiments

Time Limit : 1 sec, Memory Limit : 131072 KB
Japanese version is here

# Physical Experiments

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 $5 \times N - 5$.

## Input

The input consists of multiple datasets. Each dataset, a line, consists of the minimum velocity v (0 < v < 200) to crack the ball. The value is given by a decimal fraction, with at most 4 digits after the decimal point. The input ends with EOF. The number of datasets is less than or equal to 50.

## Output

For each dataset, print the lowest possible floor where the ball cracks.

## Sample Input

25.4
25.4


## Output for the Sample Input

8
8


Source: PC Koshien 2003 , All-Japan High School Programming Contest, Aizu-Wakamatsu, Japan, 2003
http://www.pref.fukushima.jp/pc-concours/