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

using pint = pair< int, int >;
using ull = unsigned long long;

int main()
{
    vector< int > v( 6 );
    
    for( auto&& i : v ) {
        cin >> i;
    }
    
    sort( begin( v ), end( v ) );
    v.erase( begin( v ) );
    v.erase( end( v ) - 1 );
    
    cout << fixed << setprecision( 2 ) << ( accumulate( begin( v ), end( v ), 0.0 ) / 4.0 ) << endl;
}