Go: package main

import (
	"bufio"
	"os"
	"strconv"
	"fmt"
)

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	for scanner.Scan() {
		a, _ := strconv.ParseFloat(scanner.Text(), 64)
			t := a/9.8
			x := t*t*4.9
			ans := (x+5)/5+1
			fmt.Printf("%d\n", int(ans))
	}
}

C++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
// #define main int main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
#define stlice(from, to) substr(from, (to) - (from) + 1)
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
using namespace std;
using pii = pair<int, int>;
using vi = vector<int>;
using vd = vector<double>;
using vc = vector<char>;
using vb = vector<bool>;
using vs = vector<string>;
using vpii = vector<pii>;
using vvi = vector<vi>;
using vvb = vector<vb>;
using vvpii = vector<vpii>;
template<typename A> using fn = function<A>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int &n) { return n & 1; }
constexpr bool even(const int &n) { return !odd(n); }
template<typename V> constexpr typename V::value_type sum(const V &v) { return accumulate(all(v), 0); }
void solve();
main { solve(); return 0; }
// clang-format on

void solve() {
	double v;
	while(cin >> v) {
		double t = v / 9.8;
		double y = 4.9 * t * t;
		cout << ((int)ceil(y)+10) / 5 << endl;
	}
}

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

int main() {
  double v;
  while(cin >> v) {
    double N = (v*v)/98+1;
    if(N != (int)N) N++;
    cout << (int)N << endl;
  }
  return 0;
}

C++: #include <cstdio>

using namespace std;

int main(){
	
	double v,t,y;
	int N;
	
	while (scanf("%lf",&v)!=EOF){
	
		t=v/9.8;
		y=4.9*t*t;
		N=(int)(y+5)/5;
		
		printf("%d\n",N+1);
	}
		
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
static const double g = 9.8;

double v, t, h;

int main(){
	while(cin >> v){
		t = v / g;
		h = 0.5 * g * t * t;
		//cout << t << " " << h << endl;
		int N = 0;
		while(1){
			if(5 * (N - 1) - 5 <= h && 5 * N - 5 > h) break;
			N++;
		}
		cout << N << endl;
	}
	return 0;
}

C++: #include <stdio.h>
int main(){
	double v,n;
	while(scanf("%lf",&v)!=EOF){
		n = (v*v)/98+1;
		if(n>(double)((int)n)) printf("%d\n",(int)n+1);
		else printf("%d\n",(int)n);
	}
	return 0;
}

C++: #include <stdio.h>
 
int main(void){
	double v,t,y,n1;
	int n;
	while(scanf(" %lf",&v)!=EOF){
    	t=v/9.8;
    	y=4.9*t*t;
    	n=0;
    	n1=(5+y)/5;
    	while(n<n1){
    		n=n+1;
    	}
		printf("%d\n",n);
    }
	return 0;
}

//debug for alfa

C++: #include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <deque>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <bitset>
#include <algorithm>
#include <numeric>
#include <complex>
#include <functional>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <cctype>

using namespace std;

#define dump(n) cout<<"# "<<#n<<"="<<(n)<<endl
#define debug(n) cout<<__FILE__<<","<<__LINE__<<": #"<<#n<<"="<<(n)<<endl
#define repi(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,n) repi(i,0,n)
#define iter(c) __typeof((c).begin())
#define tr(c,i) for(iter(c) i=(c).begin();i!=(c).end();i++)
#define allof(c) (c).begin(),(c).end()
#define mp make_pair

typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int,int> pii;

int main()
{
	for(double v;cin>>v;){
		int n=ceil(v*v/98+1)+1e-10;
		cout<<n<<endl;
	}
	
	return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <stack>
#include <string>
#include <cmath>
#include <cstdio>
using namespace std;

#define PI 4*atan(1);

int main(){
  double v, y, t;
  while(cin >> v){
    for(int i = 1;; i++){
      y = 5 * i - 5;
      // y = 4.9 * t * t;
      t =  sqrt(y / 4.9);
      if(9.8 * t >= v){
        cout << i << endl;
        break;
      }
    }
  }
}

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

int main() {
  int i;
  double v,vmin;
  while(cin >> vmin) {
    i=1;
    while(1) {
      v = 9.8 * sqrt((5*i-5)/4.9);
        if(v >= vmin) break;
        i++;
    }
    cout << i << endl;
  }
}

C++: #include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;
int main(){
    double x,y,i,s,n,s1;
    while( scanf("%lf", &n)!=EOF){
           
           y=(n*n)/19.6;
           if(n>1)
           cout <<int ((y+5)/5)+1<<endl;                         
           else
           cout <<"1";
           
    }
    return 0;
        
}

C++: #include<stdio.h>
#define EPS 1e-9
double v;

int main(){
	double h;
	int ans;
	while( scanf("%lf",&v) != EOF )
	{
		h = (v*v)/19.6;
		ans = h/5.0;
		h -= ans*5.0;
		if( h > EPS )
			ans++;
		ans++;
		
		printf("%d\n",ans);
	}
	return 0;
}

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

int main()
{
  double v0;
  while (scanf("%lf ", &v0) == 1) {
    cout << (int)((v0 * v0)/ (5.0 * 4.0 * 4.9) + 0.5) + 1 << endl;
  }
}

C++: #include<iostream>
#include<algorithm>
#include<string>
#include<math.h>
using namespace std;

int keta(int x){
	int i=0;
	while (x/pow(10,i)>=1){
		i++;
	}
	if (x==0){
		return 1;
	}
	else
	return i;
	}


int main(){
double min;
while (cin>>min){
	double y;
	int N;
	y=4.9*(min/9.8)*(min/9.8);
	N=ceil((y+5)/5);
	cout<<N<<endl;

}

}

C++: #include <iostream>
#include <math.h>
using namespace std;
int main()
{
	double v;
	double c = 4.9 / 9.8 / 9.8 / 5.0;
	while (cin >> v){
		int floor = int(ceil(c * v * v)) + 1;
		cout << floor << "\n";
	}
	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;

		for(int i=0;i<1000;i++){

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

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

			if(v*v>vv) l=h;
			else if(v*v<vv) r=h;
		}

		if( v*v<=2.0*9.8*(5*l-5) ) cout<<l<<endl;
		else cout<<r<<endl;

	}

	return 0;
}

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

using namespace std;

int main()
{
    double v;

    while (scanf("%lf", &v) != EOF) {
        double ans = (v*v/98);
        if (ans - (int)ans < 0.0000000001) {
            printf("%d\n", (int)ans + 1);
        } else {
            printf("%d\n", (int)ans + 2);
        }

    }

    return 0;
}

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

using namespace std;

int main()
{
    double v;

    while (scanf("%lf", &v) != EOF) {
        double ans = (v*v/98);
        if (ans - (int)ans < 0.00000000001) {
            printf("%d\n", (int)ans + 1);
        } else {
            printf("%d\n", (int)ans + 2);
        }

    }

    return 0;
}

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

const int INF = 1e+9 * 2;
double eps = 1e-10;

int main() {
	long double v;
	while(cin >> v){
		long double n = (4.9 * pow(v / 9.8, 2.0) + 5.0) / 5.0;
		if(n - (int)n < eps)
			cout << (int)n << endl;
		else
			cout << (int)n + 1 << endl;
	}
	return 0;
}