#include <atcoder/segtree>
#include <atcoder/modint>
#include <bits/stdc++.h>
using namespace std;

using Mint = atcoder::modint998244353;
Mint add(Mint a, Mint b)
{
    return a + b;
}
Mint e() { return 0; }
using Seg = atcoder::segtree<Mint, add, e>;

int main()
{
    int N;
    cin >> N;
    vector<int> X, Y;
    for (int i = 0; i < N; ++i)
    {
        int a, b;
        cin >> a >> b;
        X.emplace_back(a + b);
        Y.emplace_back(a - b);
    }
    vector<int> xc = X, yc = Y;
    sort(xc.begin(), xc.end());
    xc.erase(unique(xc.begin(), xc.end()), xc.end());
    sort(yc.begin(), yc.end());
    yc.erase(unique(yc.begin(), yc.end()), yc.end());
    for (int &x : X)
        x = lower_bound(xc.begin(), xc.end(), x) - xc.begin();
    for (int &y : Y)
        y = lower_bound(yc.begin(), yc.end(), y) - yc.begin();
    if (X[0] > X[N - 1])
        for (int &x : X)
            x = (int)xc.size() - x - 1;
    if (Y[0] > Y[N - 1])
        for (int &y : Y)
            y = (int)yc.size() - y - 1;

    vector<int> ord(N);
    iota(ord.begin(), ord.end(), 0);
    sort(ord.begin(), ord.end(), [&](int a, int b)
         { return make_pair(X[a], Y[a]) < make_pair(X[b], Y[b]); });
    Seg seg(Y.size());
    for (int a : ord)
    {
        int x = X[a], y = Y[a];
        if (a == N - 1)
        {
            cout << seg.prod(0, y + 1).val() << endl;
            return 0;
        }
        if (a == 0)
            seg.set(y, 1);
        else
            seg.set(y, seg.prod(0, y + 1) + seg.get(y));
    }
}