#include<iostream>
using namespace std;
int main(void){
	int c,n;
	double v,y;
	while(cin>>v,v!='\0'){
		y=4.9*((v*v)/(9.8*9.8));
		n=1;
		while(1){
			if(y<5*n-5)break;
			n++;
		}
		cout<<n<<endl;
	}
	

}