#include <cstdio>
#include <string>
#include <vector>
#include <map>
#include <cmath>
#include <algorithm>

using namespace std;

int main()
{
    double p,q,r,pq,bmcm,bm,cm;
    scanf ("%lf%lf%lf",&p,&q,&r);
    if ( p != r ) { printf ("0\n"); return 0; }
    pq = p + q;
    bmcm = p*pq;

    double l = 0.0001,m1,m2,ans1,ans2; r = 10000*bmcm;
    while ( r - l >= 0.0001 )
    { //printf ("%lf %lf\n",l,r);
        m1 = ( r - l ) / 3 + l;
        m2 = m1 + ( r - l ) / 3;
        ans1 = p*m1 + pq*( bmcm / m1 );
        ans2 = p*m2 + pq*( bmcm / m2 );
        if ( ans1 < ans2 ) r = m2;
        else l = m1;
    }

    cm = l; bm = bmcm / cm; //printf ("%lf %lf\n",bm,cm);

    printf("%.4lf\n",sqrt( 2*pq*pq*p*p + cm*cm*p*p + bm*bm*pq*pq ));
}
