local mfl, mce = math.floor, math.ceil
local mmi, mma = math.min, math.max
local bls, brs = bit.lshift, bit.rshift
local SegTree = {}
SegTree.updateAll = function(self)
  for i = self.stagenum - 1, 1, -1 do
    local cnt = bls(1, i - 1)
    for j = 1, cnt do
      self.stage[i][j] = self.func(self.stage[i + 1][j * 2 - 1], self.stage[i + 1][j * 2])
    end
  end
end
SegTree.create = function(self, n, func, emptyvalue)
  self.func, self.emptyvalue = func, emptyvalue
  local stagenum, mul = 1, 1
  self.stage = {{}}
  while mul < n do
    mul, stagenum = mul * 2, stagenum + 1
    self.stage[stagenum] = {}
  end
  self.stagenum = stagenum
  for i = 1, mul do self.stage[stagenum][i] = emptyvalue end
  self:updateAll()
end
SegTree.getRange = function(self, left, right)
  if left == right then return self.stage[self.stagenum][left] end
  local stagenum = self.stagenum
  local ret = self.emptyvalue
  while left <= right do
    local stage, sz = 1, bls(1, stagenum - 1)
    local len = right - left + 1
    while (left - 1) % sz ~= 0 or len < sz do
      stage, sz = stage + 1, brs(sz, 1)
    end
    ret = self.func(ret, self.stage[stage][1 + brs(left - 1, stagenum - stage)])
    left = left + sz
  end
  return ret
end
SegTree.setValue = function(self, idx, value, silent)
  self.stage[self.stagenum][idx] = value
  if not silent then
    for i = self.stagenum - 1, 1, -1 do
      local dst = brs(idx + 1, 1)
      local rem = dst * 4 - 1 - idx
      self.stage[i][dst] = self.func(self.stage[i + 1][idx], self.stage[i + 1][rem])
      idx = dst
    end
  end
end
SegTree.new = function(n, func, emptyvalue)
  local obj = {}
  setmetatable(obj, {__index = SegTree})
  obj:create(n, func, emptyvalue)
  return obj
end

local function comp(a, b)
  return a[1] < b
end

local function lower_bound(ary, x)
  local num = #ary
  if num == 0 then return 1 end
  if not comp(ary[1], x) then return 1 end
  if comp(ary[num], x) then return num + 1 end
  local min, max = 1, num
  while 1 < max - min do
    local mid = mfl((min + max) / 2)
    if comp(ary[mid], x) then
      min = mid
    else
      max = mid
    end
  end
  return max
end

local mod = 998244353
local function badd(x, y) return (x + y) % mod end

local n = io.read("*n")
local t = {}
for i = 1, n do
  t[i] = {}
  t[i][1], t[i][2] = io.read("*n", "*n")
end
table.sort(t, function(a, b) return a[1] < b[1] end)
t[n + 1] = {3 * 1000000007, 0}

local stReach = SegTree.new(n + 1, mma, 0)
for i = 1, n + 1 do
  stReach:setValue(i, i)
end

local dp = {}
for i = 1, n + 1 do
  dp[i] = 0
end
dp[n + 1] = 1
for i = n, 1, -1 do
  local dstLen = lower_bound(t, t[i][1] + t[i][2])
  local dstPos = stReach:getRange(i, dstLen - 1)
  stReach:setValue(i, dstPos)
  dp[i] = badd(dp[dstPos + 1], dp[i + 1])
end
print(dp[1])
