#include<bits/stdc++.h>
#include<vector>
#include<list>
#include<stack>
#include<queue>
#include<algorithm>
using namespace std;

int main(){
    int mod=1000000007;
    int n;
    int ans;
    double v;
    while (scanf("%lf",&v)!=EOF) {
        for (int i=0;;i++) {
            double t=v/9.8;
            double y=t*t*4.9;
            n=(int)floor((y+5.0)/5.0);
            int tmp;
            for (int j=1;;j++) {
                if (j*5-5>=y) {
                    tmp=j;
                    break;
                }
            }
            printf("%d\n",tmp);
        }
    }
    return 0;
}