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

signed main(){
  vector< int > scr( 6 );
  for( int i = 0; i < 6; ++i )
    cin >> scr[ i ];
  sort( scr.begin(), scr.end() );
  double ans = 0.0;
  for( int i = 1; i < 5; ++i )
    ans += scr[ i ];
  cout << fixed << setprecision( 2 ) << ans / 4 << endl;
  return 0;
}