#include <iostream>
#include <iomanip>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>
#include <sstream>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <numeric>
#include <cmath>
#include <climits>
#include <limits>
#include <cfloat>
#include <fstream>
using namespace std;

int main()
{ 
	double v;
	double y,t;
	int N;
        while(1){
		cin>>v;
 		if(cin.eof()) return 0;
		t=v/9.8;
		y=4.9*t*t;
                N=1+(int)y/5.0;
		if((double)5.0*(N-1)==N) cout<<N<<endl;
		else cout<<(N+1)<<endl;
	}
}