local bor = bit.bor
local n = io.read("*n")
local a = {}
for i = 1, n do
  a[i] = io.read("*n")
end
if 16 <= n then
  print(65535)
  os.exit()
end
local dp1, dp2 = {}, {}
for i = 1, 65536 do
  dp1[i] = false
end
dp1[1] = true
for i = 1, n do
  local src = i % 2 == 1 and dp1 or dp2
  local dst = i % 2 == 1 and dp2 or dp1
  for j = 1, 65536 do
    dst[j] = false
  end
  local ai = a[i]
  for j = 1, 65536 do
    if src[j] then
      for k = 1, 16 do
        local z = bor(j - 1, ai)
        dst[z + 1] = true
        ai = math.floor(ai / 2) + (ai % 2) * 32768
      end
    end
  end
end
local tbl = n % 2 == 1 and dp2 or dp1
for j = 65536, 1, -1 do
  if tbl[j] then
    print(j - 1)
    os.exit()
  end
end