def f(n,u,c)
	res=[0]
	$gs[n].each{|u2|
		next if u==u2
		res<<f(u2,n,c+1)
	}
	res=res.sort.reverse[0,2]
	res2=[c]
	res3=[0]
	if res.size>0 then
		res3<<res.max
		res2<<res.max
	end
	res<<c
	s1=res.size
	
	s1.times{|i|
		(i+1).upto(s1-1){|j|
			res2<<res[i]+res[j]
		}
	}
	$dell=[$dell,res2.max].max
	return res3.max+1
end
$dell=0
n=gets.to_i
$gs=[]
(n+1).times{
	$gs<<[]
}

(n-1).times{|i|
	a,b=gets.split(" ").map{|e| e.to_i}
	$gs[a]<<b
	$gs[b]<<a
}
1.upto(n){|s|
	if $gs[s].size==1 then
		f(s,-1,0)
		break
	end
}
puts n-1-$dell