MODE = "stdio"

tmp = Array.new




if(defined? MODE)
  tmp = STDIN.read.split("\n")
else
  iotmp = "\
  26
  ".split("\n")
  iotmp.each{|s|
    tmp << s.strip
  }
end


N = tmp[0].to_i



a = N/25
b = N%25

puts ('A'..'Z').to_a[b-1]*(a+1)