Physical Experiments

Time Limit : 1 sec, Memory Limit : 65536 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/