/* -*- coding: utf-8 -*-
 *
 * 1230.cc:  No.1230 Hall_and_me - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int N = 3;

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int ps[N], sum = 0;
  for (int i = 0; i < N; i++) {
    scanf("%d", ps + i);
    sum += ps[i];
  }
  sort(ps, ps + N);

  printf("%.12lf\n", (double)(sum - ps[0]) / sum);
  return 0;
}