#include<stdio.h>#include<math.h>#include<algorithm>using namespace std;const double eps=1e-6;double l,r,c,x,y;double equ(const double &x,const double &y,const double &mid){return 1.0/sqrt(x*x-mid*mid)+1.0/sqrt(y*y-mid*mid);}int main(){while ( scanf("%lf%lf%lf",&x,&y,&c)!=EOF ){l=0; r=min(x,y);c=1/c;while ( l-r<-eps ){double mid=(l+r)/2;if ( equ(x,y,mid)<c )l=mid;else r=mid;}printf("%.3lfn",l);}}
