f,g,h=
  ->s,m,d{
    n=s.size
    (n-(d ? 1:0)).downto(1).reduce(0){|r,i|
      i<=r&&n-i<=r&&m<=r and break r
      h[s[0,i]] or next r
      n-i<=i||n-i<=m ?
        g[s[i..-1]] ? [i,m].max : r :
        [r,f[s[i..-1],[i,m].max,false]].max
    }
  },
  ->s{
    s.size<2||s.size.downto(1).any?{|i|h[s[0,i]]&&g[s[i..-1]]}
  },
  ->s{
    s==s.reverse
  }
p f[gets.chomp,0,true]