#include <iostream>
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

#define EPS (1e-10)
#define EQ(a,b) (abs((a) - (b)) < EPS)

int main(){

	double v;

	while(cin>>v){
		double t = v/9.8;
		double y = 4.9*t*t;
		if(EQ(y,0))
			cout<<1<<endl;
		else
			cout<<(int)(y/5)+2<<endl;
	}
		
	return 0;
}