let split_string ?(pattern="") = Str.split @@ Str.regexp pattern
let s = read_line () |> split_string
let t = read_line () |> split_string

let rec loop sum s t = match (s, t) with
  | s :: sx, t :: tx -> loop (sum + if s = t then 0 else 1) sx tx
  | _ -> sum

let () = Printf.printf "%d\n" @@ loop 0 s t