import std.stdio;
import std.string, std.conv, std.array, std.algorithm;
import std.uni;

void main(){
    auto N = readln.chomp.to!int;
    auto A = readln.split.map!(to!int).array.sort();
    double ans;

    if(N % 2){
        ans = A[N / 2];
    } else {
        ans = 1.*(A[N / 2] + A[N / 2 - 1]) / 2;
    }

    writefln("%.1f", ans);
}