#include<stdio.h>
#include<iomanip>
#include<iostream>
#include<math.h>
#include<string.h>
#include<algorithm>
using namespace std;

int main()
{
    double v,t,a,x;
    a=9.8;
    while(cin>>v)
    {
        t= v/a;
        x=(a* pow(t,2))*.5;


        int result=0;
        result=(int)x/5;
        int y=x;
        if(y<x)
        result++;

        cout<<result+1<<endl;
    }
        return 0;
}