n = gets.to_i
x = []
y = []
n.times do 
    a, b = gets.split.map &:to_i
    x << a
    y << b
end
p Math.sqrt((0..n-1).to_a.combination(2).map {|p1, p2|
    (x[p1] - x[p2]) ** 2 + (y[p1] - y[p2]) ** 2
}.max) / 2