#include <bits/stdc++.h>
using namespace std;

//--------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define LL long long
#define INF INT_MAX/3

//--------------------------------------------
const double EPS = 1e-14;
const double PI  = acos(-1.0);

//--------------------------------------------

int main(){
  double s[6];
  REP (i, 6) scanf("%lf",&s[i]);
  sort(s, s+6);
  double sum = 0;
  FOR (i, 1, 5) sum += s[i];
  printf("%.2lf\n",sum / 4);
}