#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
double v;
int ans;
const double eps=1e-9;
int main()
{
    while(scanf("%lf",&v)!=EOF)
    {
        ans=ceil(v*v/19.8*0.2)+1;
        cout<<ans<<endl;
    }
    return 0;
}