#include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;
int main(){
    double x,y,i,s,n,s1;
    while( scanf("%lf", &n)!=EOF){
           
           y=(n*n)/19.6;
           if(n>1)
           cout <<int ((y+5)/5)+1<<endl;                         
           else
           cout <<"1";
           
    }
    return 0;
        
}