n=gets.to_i
a=[0]+gets.split.map(&:to_i)+[0]
p (0..n).inject([0,1].map{(0..n+1).map{0}}){|d,w|[0,1].map{|s|(0..n-w).map{|i|[d[s][i+1-s],(-1)**s==(a[i]<=>a[i+w+1])?1+d[1-s][i+s]:0].max}}}.max[0]