/*AOJ 0024*/

#include<iostream>
using namespace std;

int f(double v){
	double t = v/9.8;

	double y = 4.9 * t * t;

	int ans = (y / 5);

	if(y == (int)y){
		return ans+1;
	}
	else{
		return ans+2;
	}
}


int main(){

	double v;

	while(cin>>v){
		cout<<f(v)<<endl;
	}

	return 0;
}