N = gets.to_i
edges = (0..N).map{[]}
$<.each{|s|
	u, v = s.split.map &:to_i
	edges[u] << v
	edges[v] << u
}


while edges.any?{|e| e.size == 1 }
	(0..N).each{|u|
		if edges[u].size == 1
			v = edges[u][0]
			edges[v].each{|vv|
				edges[vv].delete v
			}
		end
	}
end

p edges.count{|e| e.size == 0} - 1