#include <iostream>
#include <cmath>

using namespace std;

const double g=9.8;
int Height(double v);

int main(){
	double v;	
	
	while( cin>>v ){
		cout<<Height(v)<<endl;
	}
	return 0;
}

int Height(double v){
	int floor;
	for( floor=0;sqrt(2*g*floor*5)<v;floor++ );
	return floor+1;
}