using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Text;
using System.Linq;

using E = System.Linq.Enumerable;

internal partial class Solver {
    struct Robot {
        public long X, D;
    }
    public void Run() {
        var n = ni();
        var x = new int[n];
        var d = new int[n];
        for (int i = 0; i < n; i++) {
            x[i] = ni();
            d[i] = ni();
        }
        var robots = E.Range(0, n)
            .Select(i => new Robot { X = x[i], D = d[i] })
            .OrderBy(r => r.X)
            .ToArray();

        int mod = 998244353;

        var dp = new long[n + 1];
        dp[n] = 1;
        var seg = new SegmentTree<int>(Math.Max, -11111);
        seg.Build(n, i => -11111);

        var sortedX = robots.Select(r => r.X).ToArray();
        long sum = 0;
        for (int i = n - 1; i >= 0; i--) {
            var begin = LowerBound(sortedX, robots[i].X);
            var end = LowerBound(sortedX, robots[i].X + robots[i].D);
            seg[i] = i;
            var until = seg[i] = seg.Query(begin, end);
            dp[i] += dp[until + 1]; // choose i
            dp[i] += dp[i + 1]; // not choose
            dp[i] %= mod;
            sum += dp[i];
            sum %= mod;
        }

        cout.WriteLine(dp[0]);
    }

    public static int LowerBound<T>(IList<T> A, T x) { return LowerBound(A, 0, A.Count, x); }
    public static int LowerBound<T>(IList<T> A, T x, Comparison<T> comp) { return LowerBound(A, 0, A.Count, x, comp); }
    public static int LowerBound<T>(IList<T> A, int start, int end, T x) { return LowerBound(A, start, end, x, Comparer<T>.Default.Compare); }
    public static int LowerBound<T>(IList<T> A, int start, int end, T x, Comparison<T> comparer) {
        int lower = start, upper = end - 1;
        int result = end;
        while (lower <= upper) {
            int pos = (lower + upper) >> 1;
            if (comparer(x, A[pos]) <= 0) {
                result = pos;
                upper = pos - 1;
            } else {
                lower = pos + 1;
            }
        }
        return result;
    }

}

public sealed class SegmentTree<TMonoid> {
    public int Count { get; private set; }
    private TMonoid[] _node;
    private readonly TMonoid _identity;
    private readonly Func<TMonoid, TMonoid, TMonoid> _merge;

    public SegmentTree(Func<TMonoid, TMonoid, TMonoid> merge, TMonoid identity) {
        _merge = merge;
        _identity = identity;
    }

    public void Build(IList<TMonoid> array) {
        Build(array.Count, i => array[i]);
    }

    public void Build(int n, Func<int, TMonoid> create) {
        Count = n;

        _node = new TMonoid[2 * Count];

        for (int i = 0; i < n; i++) {
            _node[i + Count] = create(i);
        }

        for (int i = Count - 1; i > 0; i--) {
            _node[i] = _merge(_node[i << 1], _node[i << 1 | 1]);
        }
    }

    public void Set(int index, TMonoid val) {
        int p = index + Count;
        _node[p] = val;
        while (p > 0) {
            p >>= 1;
            _node[p] = _merge(_node[p << 1], _node[p << 1 | 1]);
        }
    }

    public TMonoid Query(int begin, int end) {
        TMonoid lv = _identity, rv = _identity;
        int l = begin + Count;
        int r = end + Count - 1;
        for (; l <= r; l >>= 1, r >>= 1) {
            if ((l & 1) == 1) { lv = _merge(lv, _node[l++]); }
            if ((r & 1) == 0) { rv = _merge(_node[r--], rv); }
        }
        return _merge(lv, rv);
    }

    public TMonoid this[int index] {
        get { return _node[index + Count]; }
        set { Set(index, value); }
    }
};
// PREWRITEN CODE BEGINS FROM HERE
internal partial class Solver : Scanner {
    public static void Main(string[] args) {
#if LOCAL
        byte[] inputBuffer = new byte[1000000];
        var inputStream = Console.OpenStandardInput(inputBuffer.Length);
        using (var reader = new StreamReader(inputStream, Console.InputEncoding, false, inputBuffer.Length)) {
            Console.SetIn(reader);
            new Solver(Console.In, Console.Out).Run();
        }
#else
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        new Solver(Console.In, Console.Out).Run();
        Console.Out.Flush();
#endif
    }

#pragma warning disable IDE0052
    private readonly TextReader cin;
    private readonly TextWriter cout;
#pragma warning restore IDE0052

    public Solver(TextReader reader, TextWriter writer)
        : base(reader) {
        cin = reader;
        cout = writer;
    }
    public Solver(string input, TextWriter writer)
        : this(new StringReader(input), writer) {
    }

#pragma warning disable IDE1006
#pragma warning disable IDE0051
    private int ni() { return NextInt(); }
    private int[] ni(int n) { return NextIntArray(n); }
    private long nl() { return NextLong(); }
    private long[] nl(int n) { return NextLongArray(n); }
    private double nd() { return NextDouble(); }
    private double[] nd(int n) { return NextDoubleArray(n); }
    private string ns() { return Next(); }
    private string[] ns(int n) { return NextArray(n); }
#pragma warning restore IDE1006
#pragma warning restore IDE0051
}

internal static class LinqPadExtension {
    [Conditional("DEBUG")]
    public static void Dump<T>(this T obj) {
#if DEBUG
        LINQPad.Extensions.Dump(obj);
#endif
    }
}

public class Scanner {
    private readonly TextReader Reader;
    private readonly CultureInfo ci = CultureInfo.InvariantCulture;

    private readonly char[] buffer = new char[2 * 1024];
    private int cursor = 0, length = 0;
    private string Token;
    private readonly StringBuilder sb = new StringBuilder(1024);

    public Scanner()
        : this(Console.In) {
    }

    public Scanner(TextReader reader) {
        Reader = reader;
    }

    public int NextInt() { return checked((int)NextLong()); }
    public long NextLong() {
        var s = Next();
        long r = 0;
        int i = 0;
        bool negative = false;
        if (s[i] == '-') {
            negative = true;
            i++;
        }
        for (; i < s.Length; i++) {
            r = r * 10 + (s[i] - '0');
#if DEBUG
            if (!char.IsDigit(s[i])) throw new FormatException();
#endif
        }
        return negative ? -r : r;
    }
    public double NextDouble() { return double.Parse(Next(), ci); }
    public string[] NextArray(int size) {
        string[] array = new string[size];
        for (int i = 0; i < size; i++) {
            array[i] = Next();
        }

        return array;
    }
    public int[] NextIntArray(int size) {
        int[] array = new int[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextInt();
        }

        return array;
    }

    public long[] NextLongArray(int size) {
        long[] array = new long[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextLong();
        }

        return array;
    }

    public double[] NextDoubleArray(int size) {
        double[] array = new double[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextDouble();
        }

        return array;
    }

    public string Next() {
        if (Token == null) {
            if (!StockToken()) {
                throw new InvalidOperationException();
            }
        }
        var token = Token;
        Token = null;
        return token;
    }

    public bool HasNext() {
        if (Token != null) {
            return true;
        }

        return StockToken();
    }

    private bool StockToken() {
        while (true) {
            sb.Clear();
            while (true) {
                if (cursor >= length) {
                    cursor = 0;
                    if ((length = Reader.Read(buffer, 0, buffer.Length)) <= 0) {
                        break;
                    }
                }
                var c = buffer[cursor++];
                if (33 <= c && c <= 126) {
                    sb.Append(c);
                } else {
                    if (sb.Length > 0) break;
                }
            }

            if (sb.Length > 0) {
                Token = sb.ToString();
                return true;
            }

            return false;
        }
    }
}

Measured memory_bytes: 40924