//物理数学题

#include<stdio.h>

#include<string.h>

#include<algorithm>

using namespace std;

int main()

{

    double h,l,v,ans;

    while(scanf("%lf%lf%lf",&h,&l,&v)!=EOF)

    {

        if(h==&&l==&&v==)break;

        ans = h + v * v / 19.6 - 4.9 * l * l / v / v;

        printf("%.2lf\n",ans);

    }

    return ;

}