local mfl, mce = math.floor, math.ceil
local q = io.read("*n", "*l")
local ps, ms = {}, {}
for i = 1, 25 do
  ps[i] = 0
  ms[i] = 0
end
for iq = 1, q do
  local s = io.read()
  local t = nil
  if s:sub(1, 1) == "-" then
    t = ms
    s = s:sub(2, #s)
  else
    t = ps
  end
  if s:find("%.") then
    local s1, s2 = s:match("(%d+)%.(%d+)")
    for i = 1, #s2 do
      local v = s2:sub(i, i):byte() - 48
      t[i + 15] = t[i + 15] + v
    end
    for i = 1, #s1 do
      local v = s1:sub(i, i):byte() - 48
      t[15 - #s1 + i] = t[15 - #s1 + i] + v
    end
  else
    for i = 1, #s do
      local v = s:sub(i, i):byte() - 48
      t[15 - #s + i] = t[15 - #s + i] + v
    end
  end
end
for i = 25, 2, -1 do
  if 10 <= ps[i] then
    local up = mfl(ps[i] / 10)
    ps[i] = ps[i] % 10
    ps[i - 1] = ps[i - 1] + up
  end
  if 10 <= ms[i] then
    local up = mfl(ms[i] / 10)
    ms[i] = ms[i] % 10
    ms[i - 1] = ms[i - 1] + up
  end
end
local t1, t2 = nil, nil
local flag = true
for i = 1, 25 do
  if ms[i] < ps[i] then
    break
  elseif ps[i] < ms[i] then
    flag = false
    break
  end
end
if flag then
  t1, t2 = ps, ms
else
  t1, t2 = ms, ps
end
for i = 25, 2, -1 do
  t1[i] = t1[i] - t2[i]
  while t1[i] < 0 do
    t1[i] = t1[i] + 10
    t1[i - 1] = t1[i - 1] - 1
  end
end
if not flag then
  io.write("-")
end
local first_point = 15
for i = 1, 14 do
  if 0 < t1[i] then
    first_point = i break
  end
end
for i = first_point, 15 do
  io.write(t1[i])
end
io.write(".")
for i = 16, 25 do
  io.write(t1[i])
end
io.write("\n")