s = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_.-"

def h(c, l):
  def i(c, l):
    for x in s[:]:
      if len(c) == l-1:
        yield c+x
      else:
        i(c+x, l)
  i(c, l)

for x in i("",3): print x