(* O(2^d d) *)
let kInf = 1 lsl 60
let d, g = Scanf.scanf " %d %d" @@ fun a b -> a, b
let pcs = Array.init d @@ fun _ -> Scanf.scanf " %d %d" @@ fun a b -> a, b
let rec find r acc i bits =
  if r <= 0 then acc
  else if i < 0 then kInf
  else
    if bits lsr i land 1 = 0 then
      let pt = 100 * (i + 1) in
      let m = min (r / pt) @@ fst pcs.(i) - 1 in
      find (r - m * pt) (acc + m) (i - 1) bits
    else find r acc (i - 1) bits
let rec f sum acc i bits =
  if i >= d then find (g - sum) acc (d - 1) bits
  else
    let p, c = pcs.(i) in
    min (f sum acc (i + 1) bits) @@ f (sum + p * (i + 1) * 100 + c) (acc + p) (i + 1) (bits + 1 lsl i)
let _ = f 0 0 0 0 |> Printf.printf "%d\n"