Go: package main

import (
        "fmt"
        "math"
)

func main() {
        var v, t, h float64
        for {
                _, err := fmt.Scanf("%f", &v)
                if err != nil {
                        break
                }
                t = v / 9.8
                h = 4.9 * t * t
                n := math.Floor(h/5+1.0) + 1.0
                fmt.Printf("%d\n", int(n))
        }
}

C++: #include<iostream>
#include <fstream>
#include <stdio.h>
#include <stdlib.h>
#define _USE_MATH_DEFINES
#include <math.h>
#include<string>
#include<vector>
#include<cmath>
#include<stack>
#include<queue>
#include<sstream>
#include<algorithm>
#include<map>
#include<complex>
using namespace std;


#define li			long long int
#define rep(i,to)	for(int i=0;i<((int)(to));i++)
#define repp(i,start,to)	for(int i=(int)(start);i<((int)(to));i++)
#define pb			push_back
#define sz(v)		((li)(v).size())
#define bgn(v)		((v).begin())
#define eend(v)		((v).end())
#define allof(v)	(v).begin(), (v).end()
#define dodp(v,n)		memset(v,(li)n,sizeof(v))
#define bit(n)		(1ll<<(li)(n))
#define mp(a,b)		make_pair(a,b)
#define rin	rep(i,n)
#define EPS 1e-10
#define ETOL 1e-8
#define MOD 1000000007
#define F first
#define S second
#define p2(a,b)		cout<<a<<"\t"<<b<<endl
#define p3(a,b,c)		cout<<a<<"\t"<<b<<"\t"<<c<<endl

double v;

void solve(){
	double h=v*v/9.8/2.0;
	//cout<<h<<endl;
	
	li res=h/5;
	if(h-res*5>0)res++;
	cout<<res+1<<endl;
}

int main(){
	while(cin>>v)solve();
	
	return 0;
}

C++: #include<cstdio>
int main(){
    double s;
    while(~scanf("%lf",&s)){
        double y=(4.9*(s/9.8)*(s/9.8))+5;
        if((int)y%5==0) printf("%d\n",(int)y/5);
        else printf("%d\n",(int)y/5+1);
    }
}

C++: #include <iostream>
#include <cmath>

auto main () -> int
{
    double v;
    while (std::cin >> v)
    {
        auto t = v / 9.8;
        auto y = 4.9 * t * t;
        auto n = (y + 5) / 5;
        auto ans = std::ceil (n);
        std::cout << ans << std::endl;
    }
}

C++: #include "bits/stdc++.h"
using namespace std;
int main() {
	double v;
	while (cin >> v, v) {
		int N = 0;
		double V = 0;
		do{
			N++;
			double h = 5 * N - 5;
			V = 9.8*pow(h / 4.9, 0.5);
		} while (V < v);
		cout << N << endl;
	}
}

C++: #include <iostream>
using namespace std;

int main(){
  double v;
  int N;

  while(cin >> v){
    N = v*v/98+2;    
    cout << N << endl;
  }

  return 0;
}

C++: #include<iostream>
#include<cmath>

int main(void){
    const double g=9.8;
    double v;
    while(std::cin>>v){
        int n=1;
        if(v*v<=2*g*5*(n-1)) std::cout<<n<<std::endl;
        n++;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

using db = double;
const db eps = 1e-9;

int main() {
	ios :: sync_with_stdio(false);
	db maxv;
	while(cin >> maxv) {
		for(int i = 1; ; i ++) {
			db y = 5 * i - 5;
			db v = sqrt(y * 2 * 9.8);
			if(v + eps > maxv) {
				cout << i << '\n';
				break;
			}
		}
	}
	return 0;
}

C++: #include <iostream>
#include <cmath>
#define EPS (1e-10)
using namespace std;

int main() {
  int n;
  double v, h;
  double g = 9.8;
  while (cin >> v) {
    h = (v * v) / (2 * g);
    n = (int)ceil((h + 5) / 5 + EPS);
    cout << n << endl;
  }
  return 0;
}

C++: #include<stdio.h>

int main(){
	double a;
	
	while(~scanf("%lf",&a)){
		double t=a/9.8;
		double x=t*t*4.9;
		int ans=(x+5)/5+1;
		printf("%d\n",ans);
	}
}

C++: #include<iostream>
using namespace std;

int main(void){
  const double g = 9.8;
  const double height = 5.0;
  double v, y;
  int N;
  while(cin >> v){
    y = (v * v) / (2 * g);
    N = y / height + 1;
    if(y - ((N - 1) * height) != 0)
      N++;
    
    cout << N << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<cmath>
using namespace std;

int main(){
	double v, t, y, n;
	while(cin >> v){
		t = v / 9.8;
		y = 4.9 * t * t;
		n = (int)(ceil(y/5.0)) + 1;
		cout << n << endl;
	}
	return 0;
}

C++: #include<iostream>
using namespace std;
int main(void){
	int c,n;
	double v,y;
	while(cin>>v,v!='\0'){
		y=4.9*((v*v)/(9.8*9.8));
		n=1;
		while(1){
			if(y<5*n-5)break;
			n++;
		}
		cout<<n<<endl;
	}
	

}

C++: #include<iostream>
using namespace std;

int main() {
	double v;
	double t, y;
	int n;
	
	while( cin >> v ){
		t = v / 9.8;
		y = 4.9 * t * t;
		n = (y + 5.0 + 1e-12) / 5 + 1;
		cout << y << " " << n << endl;
	}
	return 0;
}

C++: #include<iostream>
using namespace std;
int main(){
  double v,y,t;
  int h,a,b;
  while(cin>>v){
  t = v / 9.8;
  y = 4.9 * t * t;
  h = (y+5)/5;
  a = y+5;
  b = a % 5; 
    if(b!=0) h = h + 1;
  cout << h << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <functional>
#include <set>
#include <sstream>
#include <map>

using namespace std;

const double eps=1e-10;

int main()
{
	double v;
	while(cin>>v){
		unsigned long long l=1,r=1e16,h;

		while(l+1!=r){

//			cout<<l<<" "<<r<<endl;

			h=(l+r)/2;
			double vv=2.0*9.8*(5*h-5);

			if(v*v>vv) l=h;
			else r=h;
		}
		cout<<(l+r)/2<<endl;

	}

	return 0;
}