#!/usr/bin/ruby def dfs(n,d,z) r=nil H[n].each{|e| if !z.has_key?(e) z[e]=1 r||=1<<29 x=dfs(e,d+1,z) r=[r,x+1].min z.delete(e) end } r||=0 R[n]=[r,d].min L[n]=r r end def dfs2(n,d,z) H[n].each{|e| if !z.has_key?(e) z[e]=1 dfs2(e,[d,L[n]].min+1,z) z.delete(e) end } R[n]=[R[n],d].min end n=gets.to_i H=Hash.new{|h,k|h[k]=[]} R={} L={} (n-1).times{ x,y=gets.split.map(&:to_i) H[x]<