open Printf open Scanf
module MyInt = struct
	let (+) = (+) let (-) = (-) let (/) = (/) let ( * ) = ( * ) let (mod) = (mod) let (%) = (mod) let (+=) r v = r := !r + v let (-=) r v = r := !r - v let ( *=) r v= r := !r * v let (/=) r v = r := !r / v
	(* let input_int_array n = Array.init n (fun _ -> Scanf.scanf " %d" (fun v -> v))	
	let get_int () = Scanf.scanf " %d" (fun v -> v)
	let get_2_ints () = Scanf.scanf " %d %d" (fun u v -> u,v)
	let get_3_ints () = Scanf.scanf " %d %d %d" (fun u v w -> u,v,w)
	let get_4_ints () = Scanf.scanf " %d %d %d %d" (fun u v w x -> u,v,w,x)
	let get_5_ints () = Scanf.scanf " %d %d %d %d %d" (fun u v w x y -> u,v,w,x,y)
	let print_int_endline n = n |> string_of_int |> print_endline *)
end
(* module MyInt64 = struct *)
	let (+$) = (+) let (-$) = (-) let (/$) = (/) let ( *$) = ( * )
	let (+) p q = Int64.add p q let (-) p q = Int64.sub p q let ( * ) p q = Int64.mul p q let (/) p q = Int64.div p q let (+=) r v = r := !r + v let (-=) r v = r := !r - v let ( *=) r v= r := !r * v let (/=) r v = r := !r / v
	let labs p = if p < 0L then -1L*p else p
	let (~|) p = Int64.to_int p
	let (~~|) p = Int64.of_int p

	let input_i64_array n = Array.init (~| n) (fun _ -> Scanf.scanf " %Ld" (fun v -> v))
	let get_i64 () = Scanf.scanf " %Ld" (fun v -> v)
	let get_2_i64 () = Scanf.scanf " %Ld %Ld" (fun u v -> u,v)
	let get_3_i64 () = Scanf.scanf " %Ld %Ld %Ld" (fun u v w -> u,v,w)
	let get_4_i64 () = Scanf.scanf " %Ld %Ld %Ld %Ld" (fun u v w x -> u,v,w,x)
	let get_5_i64 () = Scanf.scanf " %Ld %Ld %Ld %Ld %Ld" (fun u v w x y -> u,v,w,x,y)
	let print_i64_endline n =
		n |> Int64.to_string |> print_endline
	
	let (mod) m n = m - (m/n) * n let (%) = (mod)
	let rec gcd m n = match m,n with | m,0L -> m | m,n -> gcd n (m mod n)
	let rec lcm m n = (m*n) / gcd m n
	let rep from_ to_ fbod =
		let i,f = ref ~|from_,ref true in while !i <= ~|to_-$1 && !f do
			match fbod !i with
			| `Ok -> i := !i +$ 1;
			| `Ng -> f := false
		done
(* end open MyInt64 *)

let () =
	let n = get_i64 ()
	in let a = input_i64_array n
	in
	let lcm_minus_1 = (Array.fold_left (fun u v -> lcm u v) 1L a) - 1L
	in
	let sum = ref 0L in
	for j=0 to Array.length a -$ 1 do
		sum += lcm_minus_1 mod a.(j)
	done;
	!sum |> printf "%Ld\n"