#include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <utility>
#include <cstring>
#include <iomanip>
#include <numeric>
#include <cmath>
#include <queue>
#include <map>
using namespace std;
typedef long long ll;
const int INF = 1<<30; 
const int MOD = 1e9 + 7;
const int dy[] = {1, 0, -1, 0};
const int dx[] = {0, 1, 0, -1};
int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    double v;
    while(cin >> v)
    {
        double t = v / 9.8;
        double y = 4.9 * t * t;
        int h = 1;
        while(1)
        {
            if(y < 5 * h - 5) break;
            h++;
        }
        cout << h << endl;
    }
    return 0;
}


