#include <bits/stdc++.h>
using namespace std;
#include <math.h>
#include <iomanip>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const int INF=1001001001;
const int mod=1e9+7;

int main(){
  vector<double>t(3);
  cin>>t[0]>>t[1]>>t[2];
  sort(t.begin(),t.end());
  if(t[0]==0&&t[1]==0){cout<<1<<endl;return 0;}
  double x=t[2]/(t[0]+t[1]+t[2]);
  double y=t[1]/(t[0]+t[1]+t[2]);
  double z=t[0]/(t[0]+t[1]+t[2]);
  cout<<fixed<<setprecision(10)<<max({max(y,1-y),max(z,1-z),max(x,1-x)})<<endl;
  return 0;                       
}