#include <iostream>
#include <vector>
#include <utility>
#include <algorithm>
#include <functional>
using namespace std;

template <typename Monoid>
struct SegmentTree
{
    using F = function<Monoid(Monoid, Monoid)>;

    int sz;
    vector<Monoid> seg;

    const F f;
    const Monoid M1;

    SegmentTree(int n, const F f, const Monoid &M1) : f(f), M1(M1)
    {
        sz = 1;
        while (sz < n)
            sz <<= 1;
        seg.assign(2 * sz, M1);
    }

    void set(int k, const Monoid &x)
    {
        seg[k + sz] = x;
    }

    void build()
    {
        for (int k = sz - 1; k > 0; k--)
        {
            seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
        }
    }

    void update(int k, const Monoid &x)
    {
        k += sz;
        seg[k] = x;
        while (k >>= 1)
        {
            seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
        }
    }

    Monoid query(int a, int b)
    {
        Monoid L = M1, R = M1;
        for (a += sz, b += sz; a < b; a >>= 1, b >>= 1)
        {
            if (a & 1)
                L = f(L, seg[a++]);
            if (b & 1)
                R = f(seg[--b], R);
        }
        return f(L, R);
    }

    Monoid operator[](const int &k) const
    {
        return seg[k + sz];
    }

    template <typename C>
    int find_subtree(int a, const C &check, Monoid &M, bool type)
    {
        while (a < sz)
        {
            Monoid nxt = type ? f(seg[2 * a + type], M) : f(M, seg[2 * a + type]);
            if (check(nxt))
                a = 2 * a + type;
            else
                M = nxt, a = 2 * a + 1 - type;
        }
        return a - sz;
    }

    template <typename C>
    int find_first(int a, const C &check)
    {
        Monoid L = M1;
        if (a <= 0)
        {
            if (check(f(L, seg[1])))
                return find_subtree(1, check, L, false);
            return -1;
        }
        int b = sz;
        for (a += sz, b += sz; a < b; a >>= 1, b >>= 1)
        {
            if (a & 1)
            {
                Monoid nxt = f(L, seg[a]);
                if (check(nxt))
                    return find_subtree(a, check, L, false);
                L = nxt;
                ++a;
            }
        }
        return -1;
    }

    template <typename C>
    int find_last(int b, const C &check)
    {
        Monoid R = M1;
        if (b >= sz)
        {
            if (check(f(seg[1], R)))
                return find_subtree(1, check, R, true);
            return -1;
        }
        int a = sz;
        for (b += sz; a < b; a >>= 1, b >>= 1)
        {
            if (b & 1)
            {
                Monoid nxt = f(seg[--b], R);
                if (check(nxt))
                    return find_subtree(b, check, R, true);
                R = nxt;
            }
        }
        return -1;
    }
};

using int64 = long long;

int main() {
    int N;
    cin >> N;

    vector<pair<int64, int64>> xds;
    for (int i = 0; i < N; i++) {
        int64 X, D;
        cin >> X >> D;
        xds.emplace_back(X, D);
    }
    sort(begin(xds), end(xds));

    SegmentTree<int64> segtree(N, [](int64 a, int64 b) { return max(a, b); }, -(1LL << 60));
    for (int i = N - 1; i >= 0; i--) {
        segtree.update(i, xds[i].first + xds[i].second);
        int ub = lower_bound(begin(xds), end(xds), make_pair(segtree[i], 0LL)) - begin(xds);
        // その操作によって直接的、あるいは間接的に起動されるロボットが移動し終わったときの座標の最大値
        segtree.update(i, segtree.query(i, ub));
    }

    constexpr int64 MOD = 998244353;
    vector<int64> dp(N + 1, 0);
    dp[0] = 1;
    for (int i = 0; i < N; i++) {
        int ni = lower_bound(begin(xds), end(xds), make_pair(segtree[i], 0LL)) - begin(xds);
        (dp[ni] += dp[i]) %= MOD;
        (dp[i + 1] += dp[i]) %= MOD;
    }
    cout << dp[N] << endl;

    return 0;
}

Measured memory_bytes: 9964