import core.bitop, std.bitmanip;
import core.checkedint;
import std.algorithm, std.functional;
import std.array, std.container;
import std.bigint;
import std.conv;
import std.math, std.numeric;
import std.range, std.range.interfaces;
import std.stdio, std.string;
import std.typecons;

void main()
{
    int n;
    readf("%s", &n);
    readln;
    
    auto arr = readln.chomp.split.map!(to!double).array;
    
    auto ans = arr.sort.reduce!((x, a) => (x + a) / 2);
    
    writefln("%.12f", ans);
}