import sequtils, strutils

let
  input = stdin.lines.toSeq
  n = parseInt input[0]
  seq1 = input[1..^1]

if seq1.len != n:
  echo $'"' & "assert" & $'"'
  quit()

let
  xs = seq1.map parseInt

var
  a, b, c = 0

for x in xs:
  var tmp = x
  if tmp > a:
    swap(tmp, a)
  if tmp > b:
    swap(tmp, b)
  if tmp > c and (a != b or tmp != b):
    swap(tmp, c)

if b == c:
  echo b + c
else:
  echo a + c