import List main=interact$unlines.reverse.g.lines g x=zipWith h[1-l x..]$transpose$f x f[x]=[x] f(a:x)=[t,s]#(t++q):s:s:s:f x where s=f x#q;t=[x]#q++a q=' ':q h n|n<0=drop(-2*n)|0<1=(take(2*n)q++) a#b=take(maximum$map l a)b l=length