#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)

int S[6];
//-----------------------------------------------------------------
int main() {
	rep(i, 0, 6) cin >> S[i];
	sort(S, S + 6);

	int sum = 0;
	rep(i, 1, 5) sum += S[i];

	sum *= 100;
	sum /= 4;

	if (sum == 0) {
		printf("0.00\n");
		return 0;
	}

	string ans = to_string(sum);
	rep(i, 0, ans.length()) {
		if(i == ans.length() - 2)
			printf(".%c", ans[i]);
		else
			printf("%c", ans[i]);
	}
	printf("\n");
}