arg = {...}
if #arg == 0 then
  print("Usage: random <length>")
  return exit
end

all = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
e = ""

for i = 1, tonumber(arg[1]) do
  r = math.random(#all)
  e = e.. string.sub(all, r, r)
end

print(e)