#include <cstdio>
#include <algorithm>
#include <cmath>

using namespace std;

const double eps = 1e-5;

double p, q, r;

double get( double b ) {
    double c = (-p/b)*(p+q);
    double db = p*p + b*b, dc = (p+q)*(p+q) + c*c;
    return db*dc;
}

int main( void ) {
    scanf( "%lf %lf %lf", &p, &q, &r );
    if( fabs( p-r ) > eps ) { puts( "0" ); return 0; }

    double lo = eps, hi = 1000000000;
    for( int it = 0; it < 10000; ++it ) {
        double mid = ( lo+hi )/2;
        if( get( mid ) > get( mid+eps ) ) lo = mid; else
            hi = mid;
    }

    double ans = sqrt( get( lo ) );
    printf( "%.4lf\n", ans );
    return 0;
}