#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <sstream>
#include <cmath>
#include <bitset>
#include <utility>
#include <set>
#define INT_MAX 2147483647
#define INT_MIN -2147483648
#define pi acos(-1.0)
#define N 1000000
#define LL long long
using namespace std;
int main()
{
    double  a;
    while(cin>>a)
    {

        double y,t=a/9.8;
        y=4.9*t*t;
       double fl=5*1-5;int i=2;
        //cout<<y<<" "<<fl<<endl;

        while(y>fl)
        {
            fl=5*i-5;
            i++;
        }
        //cout<<y<<" "<<fl<<endl;
        cout<<i-1<<endl;
    }

    return 0;
}