/*
TASK:abcd
LANG:C++
*/
#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
struct elem
{
 double x,y;
};
elem a,b,c;
int main()
{
 double p,q,r,ok;
 cin>>p>>q>>r;
 if(p!=r)cout<<0<<endl;
 else
 {
  a.x=0;
  a.y=0;
  b.x=p;
  c.x=p+q;
  b.y=p;
  c.y=(b.x*c.x)/b.y;
  ok=sqrt((b.x*b.x+b.y*b.y)*(c.x*c.x+c.y*c.y));
  printf("%.4lf\n",ok);
 }
 return 0;
}
