Scanf.scanf "%d" (fun n -> let s = Array.init n (fun _ -> Scanf.scanf " %s" (fun s -> s)) in let t = Array.init n (fun _ -> Scanf.scanf " %s" (fun t -> t)) in let rec loop i = if s.(i) = t.(i) then loop (i + 1) else i in let a = loop 0 in Printf.printf "%d\n%s\n%s\n" (a + 1) s.(a) t.(a) )