local mfl, mce = math.floor, math.ceil
local mod = 1000000007
local half = 500000004
local function bmul(x, y)
  local x1, y1 = mfl(x / 31623), mfl(y / 31623)
  local x0, y0 = x - x1 * 31623, y - y1 * 31623
  return (x1 * y1 * 14122 + (x1 * y0 + x0 * y1) * 31623 + x0 * y0) % mod
end
local function badd(x, y) return (x + y) % mod end
local ret = 0
local function floorSum(n, m, a, b)
  local f = f
  while true do
    if m <= a then
      local v = mfl(a / m)
      ret = badd(ret, bmul(v, bmul(n, bmul(n - 1, half))))
      a = a % m
    end
    if m <= b then
      ret = badd(ret, bmul(n, mfl(b / m)))
      b = b % m
    end
    if a == 0 then break end
    if f then
      n, m, a, b = a + mfl(a / m), a, m, a % m
      f = false
    else
      local y = mfl((a * n + b) / m)
      local z = (a * n + b) % m
      n, m, a, b = y, a, m, z
    end
  end
end

local n, m = io.read("*n", "*n")
local a, b = {}, {}
for i = 1, n do
  a[i] = io.read("*n")
end
for i = 1, m do
  b[i] = io.read("*n")
end
for i = 1, n do
  -- if i % 100 == 0 then
    -- print(i, os.clock())
  -- end
  for j = 1, m do
    floorSum(b[j] + 1, b[j], a[i], 0)
  end
end
ret = (ret + ret) % mod
ret = tostring(ret):gsub("LL", "")
print(ret)

-- print(os.clock())