#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <climits>
#include <cmath>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <deque>
using namespace std;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef pair<int,int> pii;
typedef map<int,int> mii;
#define PI acos(-1.)
#define SQR(x) ((x)*(x))
#define INF (INT_MAX/100)
#define mid(x,y) (x+y)/2
#define ll long long
#define sz(v) ((int)(v).size())
#define rep(i, n) for (int i=0; i<(n); ++i)
#define repf(i, a, b) for (int i=(a); i<=(b); ++i)
#define repd(i, a, b) for (int i=(a); i>=(b); --i)
#define fill(a, b) memset(a, b, sizeof(a))
#define clr(q) while (!q.empty()) q.pop();
#define pb push_back
#define pf push_front
#define itr iterator
#define eps 1e-9

int sgn(double d){
    return d<-eps?-1:d>eps;
}

int main(){
    double v;
    while (~scanf("%lf", &v)){
        cout<<ceil(v*v/2/9.8/5+1)<<endl;
    }
    return 0;
}