lib C
    fun getchar_unlocked : Int32
end
def read_i : Int32
    ans = 0
    f = 1
    c = C.getchar_unlocked()
    while [9, 10, 11, 12, 13, 32].includes?(c)
        c = C.getchar_unlocked()
    end
    if c == 45
        f = -1
        c = C.getchar_unlocked()
    end
    while (48 .. 57).includes?(c)
        ans = (ans << 1) + (ans << 3) + (c ^ 48)
        c = C.getchar_unlocked()
    end
    return ans * f
end
n = read_i
a = Array(Int32).new(n) {read_i}.sort
if n & 1 == 1
    puts(a[n >> 1])
else
    printf("%.1f\n", (a[n >> 1] + a[(n >> 1) - 1]) / 2)
end