#include "bits/stdc++.h"

#define REP(i, n) for(decltype(n) i = 0; i < (n); i++)
#define REP2(i, x, n) for(decltype(x) i = (x); i < (n); i++)
#define RREP(i, n) for (decltype(n) i = (n) - 1;i >= 0; i--)

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

#define LL long long int
#define LD long double

#define PI 3.14159265358979

#define _CRT_SECURE_NO_WARNINGS

using namespace std;

//================================================
int main() {
/*
	ios::sync_with_stdio(false);
	cin.tie(0);
*/
	vector<double>vec(6);
	double sum = 0, min = 101, max = -1, ans;
	REP(i, 6) {
		cin >> vec[i];

		min = std::min(min, vec[i]);
		max = std::max(max, vec[i]);
		sum += vec[i];
	}

	ans = (sum - min) - max;
	ans /= 4;

	printf("%.2lf\n", ans);
	return 0;
}