#region いつもの
using System;
using System.Collections.Generic;
using System.Linq;
using IEnumerable = System.Collections.IEnumerable;
using IEnumerator = System.Collections.IEnumerator;
using BigInteger = System.Numerics.BigInteger;
using TextReader = System.IO.TextReader;
using static Global;
using static NumGlobal;

static class Global
{
    public static T[] NewArray<T>(int len0, T value) => new T[len0].Fill(value);
    public static T[] NewArray<T>(int len0, Func<T> factory)
    {
        var arr = new T[len0];
        for (int i = 0; i < arr.Length; i++) arr[i] = factory();
        return arr;
    }
    public static T[][] NewArray<T>(int len0, int len1, T value) where T : struct
    {
        var arr = new T[len0][];
        for (int i = 0; i < arr.Length; i++) arr[i] = NewArray(len1, value);
        return arr;
    }
    public static T[][] NewArray<T>(int len0, int len1, Func<T> factory)
    {
        var arr = new T[len0][];
        for (int i = 0; i < arr.Length; i++) arr[i] = NewArray(len1, factory);
        return arr;
    }
    public static T[][][] NewArray<T>(int len0, int len1, int len2, T value) where T : struct
    {
        var arr = new T[len0][][];
        for (int i = 0; i < arr.Length; i++) arr[i] = NewArray(len1, len2, value);
        return arr;
    }
    public static T[][][] NewArray<T>(int len0, int len1, int len2, Func<T> factory)
    {
        var arr = new T[len0][][];
        for (int i = 0; i < arr.Length; i++) arr[i] = NewArray(len1, len2, factory);
        return arr;
    }
    public static T[][][][] NewArray<T>(int len0, int len1, int len2, int len3, T value) where T : struct
    {
        var arr = new T[len0][][][];
        for (int i = 0; i < arr.Length; i++) arr[i] = NewArray(len1, len2, len3, value);
        return arr;
    }
    public static T[][][][] NewArray<T>(int len0, int len1, int len2, int len3, Func<T> factory)
    {
        var arr = new T[len0][][][];
        for (int i = 0; i < arr.Length; i++) arr[i] = NewArray(len1, len2, len3, factory);
        return arr;
    }
    private class ComparerReverseImpl<T> : Comparer<T> where T : IComparable<T> { public override int Compare(T y, T x) => x.CompareTo(y); public override bool Equals(object obj) => obj != null && GetType() == obj.GetType(); public override int GetHashCode() => GetType().GetHashCode(); }
    public static IComparer<T> ComparerReverse<T>() where T : IComparable<T> => new ComparerReverseImpl<T>();
    public static string AllLines<T>(IEnumerable<T> source) => string.Join("\n", source);
    public static string AllJoin<T>(IEnumerable<T> source) => string.Join(" ", source);
}
static class NumGlobal
{
    public static int Pow(int x, int y)
    {
        int res = 1;
        for (; y > 0; y >>= 1)
        {
            if ((y & 1) == 1) res *= x;
            x *= x;
        }
        return res;
    }
    public static BigInteger ParseBigInteger(string s)
    {
        // MonoのBigInteger.Parseが遅いので自前実装
        var res = BigInteger.Zero;
        var splited = new string[(s.Length + 7) / 8];
        for (var i = 0; i < splited.Length - 1; i++)
        {
            splited[i] = s.Substring(8 * i, 8);
        }
        splited[splited.Length - 1] = s.Substring(8 * (splited.Length - 1));
        foreach (var sp in splited)
        {
            res *= (int)Math.Pow(10, sp.Length);
            res += int.Parse(sp);
        }
        return res;
    }
    public static int BitCount(int x) { x -= (x >> 1) & 0x55555555; x = (x & 0x33333333) + ((x >> 2) & 0x33333333); x = (x + (x >> 4)) & 0x0f0f0f0f; x += x >> 8; x += x >> 16; return x & 0x3f; }
    public static int BitCount(long x) { x -= (x >> 1) & 0x5555555555555555; x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333); x = (x + (x >> 4)) & 0x0f0f0f0f0f0f0f0f; x += x >> 8; x += x >> 16; x += x >> 32; return (int)(x & 0x0000007f); }
    public static int MSB(int x) { x |= x >> 1; x |= x >> 2; x |= x >> 4; x |= x >> 8; x |= x >> 16; return BitCount(x) - 1; }
    public static int MSB(long x) { x |= x >> 1; x |= x >> 2; x |= x >> 4; x |= x >> 8; x |= x >> 16; x |= x >> 32; return BitCount(x) - 1; }
    public static int LSB(int x) { x |= x << 1; x |= x << 2; x |= x << 4; x |= x << 8; x |= x << 16; return 32 - BitCount(x); }
    public static int LSB(long x) { x |= x << 1; x |= x << 2; x |= x << 4; x |= x << 8; x |= x << 16; x |= x << 32; return 64 - BitCount(x); }
}
static class Ext
{
    public static T[] Fill<T>(this T[] arr, T value)
    {
        for (var i = 0; i < arr.Length; i++) arr[i] = value;
        return arr;
    }
    public static T[] Sort<T>(this T[] arr)
    {
        Array.Sort(arr);
        return arr;
    }
    public static string[] Sort(this string[] arr)
    {
        Array.Sort(arr, StringComparer.OrdinalIgnoreCase);
        return arr;
    }
    public static T[] Reverse<T>(this T[] arr)
    {
        Array.Reverse(arr);
        return arr;
    }

    public static Tuple<TSource, TMax> MaxBy<TSource, TMax>
        (this IEnumerable<TSource> source, Func<TSource, TMax> maxBySelector)
        where TMax : IComparable<TMax>
    {
        TMax max;
        TSource maxByItem;

        var e = source.GetEnumerator();
        e.MoveNext();
        maxByItem = e.Current;
        max = maxBySelector(maxByItem);
        while (e.MoveNext())
        {
            var item = e.Current;
            var next = maxBySelector(item);
            if (max.CompareTo(next) < 0)
            {
                max = next;
                maxByItem = item;
            }
        }
        return Tuple.Create(maxByItem, max);
    }
    public static Tuple<TSource, TMin> MinBy<TSource, TMin>
        (this IEnumerable<TSource> source, Func<TSource, TMin> minBySelector)
        where TMin : IComparable<TMin>
    {
        TMin min;
        TSource minByItem;

        var e = source.GetEnumerator();
        e.MoveNext();
        minByItem = e.Current;
        min = minBySelector(minByItem);
        while (e.MoveNext())
        {
            var item = e.Current;
            var next = minBySelector(item);
            if (min.CompareTo(next) > 0)
            {
                min = next;
                minByItem = item;
            }
        }
        return Tuple.Create(minByItem, min);
    }
    public static IComparer<T> Reverse<T>(this IComparer<T> comparer) => Comparer<T>.Create((x, y) => comparer.Compare(y, x));
    public static Dictionary<TKey, int> GroupCount<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector) => source.GroupBy(keySelector).ToDictionary(g => g.Key, g => g.Count());
    public static Dictionary<TKey, int> GroupCount<TKey>(this IEnumerable<TKey> source) => source.GroupCount(i => i);
}
#pragma warning disable CA1819
[System.Diagnostics.DebuggerNonUserCode]
public class ConsoleReader { private string[] ReadLineSplit() => textReader.ReadLine().Split(Array.Empty<char>(), StringSplitOptions.RemoveEmptyEntries); private string[] line = Array.Empty<string>(); private int linePosition; private TextReader textReader; public ConsoleReader(TextReader tr) { textReader = tr; } public int Int => int.Parse(String); public int Int0 => Int - 1; public long Long => long.Parse(String); public double Double => double.Parse(String); public string String { get { if (linePosition >= line.Length) { linePosition = 0; line = ReadLineSplit(); } return line[linePosition++]; } } public class SplitLine { public SplitLine(ConsoleReader cr) { String = cr.ReadLineSplit(); cr.line = Array.Empty<string>(); } public int[] Int => String.Select(x => int.Parse(x)).ToArray(); public int[] Int0 => String.Select(x => int.Parse(x) - 1).ToArray(); public long[] Long => String.Select(x => long.Parse(x)).ToArray(); public double[] Double => String.Select(x => double.Parse(x)).ToArray(); public string[] String { get; } } public SplitLine Split => new SplitLine(this); public class RepeatReader { ConsoleReader cr; int count; public RepeatReader(ConsoleReader cr, int count) { this.cr = cr; this.count = count; } public T[] Select<T>(Func<ConsoleReader, T> factory) { var arr = new T[count]; for (int i = 0; i < count; i++) arr[i] = factory(cr); return arr; } public string[] String => this.Select(cr => cr.String); public int[] Int => this.Select(cr => cr.Int); public int[] Int0 => this.Select(cr => cr.Int - 1); public long[] Long => this.Select(cr => cr.Long); public double[] Double => this.Select(cr => cr.Double); } public RepeatReader Repeat(int count) => new RepeatReader(this, count); }
public class Program
{
    [System.Diagnostics.DebuggerBrowsable(System.Diagnostics.DebuggerBrowsableState.Never)] private ConsoleReader cr;

    public Program(ConsoleReader consoleReader) { this.cr = consoleReader; }
    static void Main() => Console.WriteLine(new Program(new ConsoleReader(Console.In)).Calc());

    #endregion
    public object Calc()
    {
        var N = cr.Int;
        var robots = cr.Repeat(N).Select(cr => new Robot { x = cr.Int, d = cr.Int });
        Array.Sort(robots, (r1, r2) => r1.x.CompareTo(r2.x));

        var t = new int[N];
        {
            var xs = robots.Select(r => r.x).ToArray();
            for (int i = 0; i < robots.Length; i++)
                t[i] = xs.LowerBound(robots[i].x + robots[i].d);

            var seg = new SegmentTree(t);
            for (int i = t.Length - 1; i >= 0; i--)
            {
                t[i] = seg.Query(i, t[i]);
                seg.Update(i, t[i]);
            }
        }
        Mod[] dp = new Mod[N + 1];
        dp[N] = 1;
        for (int i = N - 1; i >= 0; i--)
        {
            dp[i] = dp[i + 1] + dp[t[i]];
        }
        return dp[0];
    }
}

struct Robot
{
    public int x;
    public int d;
}
static class 二分探索
{
    /// <summary>
    /// 与えられた<paramref name="predicate"/> の結果がtrueであるような最大の数値を二分法で取得します．
    /// </summary>
    /// <param name="l">最小値</param>
    /// <param name="r">最大値</param>
    /// <param name="predicate">判定条件</param>
    /// <returns><paramref name="predicate"/> がtrueを返す最大の o-indexed でのインデックス．</returns>
    /// <remarks> <paramref name="predicate"/> はある範囲以下の全ての数でtrueとなりある範囲以上でfalseとなると仮定します．この関数は O(log N) で実行されます．</remarks>
    static int Bisection(int l, int r, Predicate<int> predicate)
    {
        while (l < r)
        {
            var m = (l + r + 1) >> 1;
            if (predicate(m)) l = m;
            else r = m - 1;
        }
        return l;
    }


    static int BinarySearch<T>(IList<T> a, T v, IComparer<T> cmp, bool isLowerBound)
    {
        var l = 0;
        var r = a.Count - 1;
        while (l <= r)
        {
            var m = (l + r) >> 1;
            var res = cmp.Compare(a[m], v);
            if (res < 0 || (res == 0 && !isLowerBound)) l = m + 1;
            else r = m - 1;
        }
        return l;
    }

    /// <summary>
    /// 与えられた比較関数に従って，<paramref name="a"/> の要素のうち，<paramref name="v"/> 以上の要素であるような最小のインデックスを取得します．
    /// </summary>
    /// <typeparam name="T"><see cref="IList{T}"/> の要素の型を指定します．</typeparam>
    /// <param name="a">対象となるコレクション</param>
    /// <param name="v">対象となる要素</param>
    /// <param name="f"></param>
    /// <returns><paramref name="v"/> 以上の要素であるような最小の o-indexed でのインデックス．</returns>
    /// <remarks> <paramref name="a"/> は比較関数に対して昇順であることを仮定しています．この関数は O(log N) で実行されます．</remarks>
    public static int LowerBound<T>(this IList<T> a, T v, Comparison<T> f) => BinarySearch(a, v, Comparer<T>.Create(f), true);

    /// <summary>
    ///　デフォルトの比較関数に従って，<paramref name="a"/> の要素のうち，<paramref name="v"/> 以上の要素であるような最小のインデックスを取得します．
    /// </summary>
    /// <typeparam name="T"><see cref="IList{T}"/> の要素の型を指定します．</typeparam>
    /// <param name="a">対象となるコレクション</param>
    /// <param name="v">対象となる要素</param>
    /// <param name="f"></param>
    /// <returns><paramref name="v"/> 以上の要素であるような最小の o-indexed でのインデックス．</returns>
    /// <remarks> <paramref name="a"/> は比較関数に対して昇順であることを仮定しています．この関数は O(log N) で実行されます．</remarks>
    public static int LowerBound<T>(this IList<T> a, T v) => BinarySearch(a, v, Comparer<T>.Default, true);

    /// <summary>
    /// 与えられた比較関数に従って，<paramref name="a"/> の要素のうち，<paramref name="v"/> より真に大きい要素が現れる最小のインデックスを取得します．
    /// </summary>
    /// <typeparam name="T"><see cref="IList{T}"/> の要素の型を指定します．</typeparam>
    /// <param name="a">対象となるコレクション</param>
    /// <param name="v">対象となる要素</param>
    /// <param name="f"></param>
    /// <returns><paramref name="v"/> 以上の要素であるような最小の o-indexed でのインデックス．</returns>
    /// <remarks> <paramref name="a"/> は比較関数に対して昇順であることを仮定しています．この関数は O(log N) で実行されます．</remarks>
    public static int UpperBound<T>(this IList<T> a, T v, Comparison<T> cmp) => BinarySearch(a, v, Comparer<T>.Create(cmp), false);

    /// <summary>
    ///　デフォルトの比較関数に従って，<paramref name="a"/> の要素のうち，<paramref name="v"/> より真に大きい要素が現れる最小のインデックスを取得します．
    /// </summary>
    /// <typeparam name="T"><see cref="IList{T}"/> の要素の型を指定します．</typeparam>
    /// <param name="a">対象となるコレクション</param>
    /// <param name="v">対象となる要素</param>
    /// <param name="f"></param>
    /// <returns><paramref name="v"/> 以上の要素であるような最小の o-indexed でのインデックス．</returns>
    /// <remarks> <paramref name="a"/> は比較関数に対して昇順であることを仮定しています．この関数は O(log N) で実行されます．</remarks>
    public static int UpperBound<T>(this IList<T> a, T v) => BinarySearch(a, v, Comparer<T>.Default, false);
}

struct Mod : IEquatable<Mod>
{
    public const long mod = 998244353;
    public readonly long val;
    public Mod(long val, bool isValid) : this(isValid ? val % mod : val) { }
    public Mod(long val) { this.val = val; }
    public override bool Equals(object obj) => (obj is Mod) ? this == ((Mod)obj) : false;
    public bool Equals(Mod obj) => this == obj;
    public override int GetHashCode() => val.GetHashCode();
    public override string ToString() => val.ToString();
    public static implicit operator Mod(long x) => new Mod(x);
    public static Mod operator +(Mod x, Mod y) => (x.val + y.val) % mod;
    public static Mod operator -(Mod x, Mod y) => x.val >= y.val ? (x.val - y.val) % mod : (x.val - y.val) % mod + mod;
    public static Mod operator *(Mod x, Mod y) => (x.val * y.val) % mod;
    public static Mod operator /(Mod x, Mod y) => x * y.Inverse();
    public static bool operator ==(Mod x, Mod y) => x.val == y.val;
    public static bool operator !=(Mod x, Mod y) => x.val != y.val;
    public Mod Inverse()
    {
        long a = val, b = mod, u = 1, v = 0;
        while (b > 0)
        {
            long t = a / b;
            var b2 = a - t * b;
            a = b; b = b2;
            var v2 = u - t * v;
            u = v; v = v2;
        }
        u %= mod;
        if (u < 0) u += mod;
        return u;
    }
    public static Mod Pow(Mod x, int y)
    {
        Mod res = 1;
        for (; y > 0; y >>= 1)
        {
            if ((y & 1) == 1) res *= x;
            x *= x;
        }
        return res;
    }

    public static Factor CreateFactor(int max) => new Factor(max);
    public class Factor
    {
        private readonly Mod[] fac, finv;
        public Factor(int max)
        {
            ++max;
            var inv = new Mod[max];
            fac = new Mod[max]; finv = new Mod[max];
            fac[0] = fac[1] = 1;
            finv[0] = finv[1] = 1;
            inv[1] = 1;
            for (var i = 2; i < max; i++)
            {
                fac[i] = fac[i - 1] * i;
                inv[i] = mod - inv[mod % i].val * (mod / i) % mod;
                finv[i] = finv[i - 1] * inv[i];
            }
        }

        // 二項係数計算
        public Mod Combine(int n, int k)
        {
            if (n < k) return 0;
            if (n < 0 || k < 0) return 0;
            return fac[n] * finv[k] * finv[n - k];
        }

        public Mod Factorial(int n) => fac[n];
        public Mod FactorialInvers(int n) => finv[n];
    }
}
[System.Diagnostics.DebuggerTypeProxy(typeof(SegmentTreeDebugView))]
class SegmentTree
{
    // この辺は場合によって変える
    private int defaultValue = 0;
    private int Operate(int v1, int v2)
    {
        return Math.Max(v1, v2);
    }

    private int rootLength;
    private int[] tree;

    public SegmentTree(int[] initArray) : this(initArray.Length)
    {
        for (var i = 0; i < initArray.Length; i++)
            Update(i, initArray[i]);
    }
    public SegmentTree(int size)
    {
        for (rootLength = 1; rootLength < size; rootLength <<= 1) { }
        tree = NewArray(2 * rootLength - 1, defaultValue);
    }

    public void Update(int index, int value)
    {
        index += rootLength - 1;
        tree[index] = value;
        while (index > 0)
        {
            index = (index - 1) >> 1;
            tree[index] = Operate(tree[index * 2 + 1], tree[index * 2 + 2]);
        }
    }

    public int Query(int fromInclusive, int toExclusive)
    {
        var leftResult = defaultValue;
        var rightResult = defaultValue;
        var l = fromInclusive + rootLength - 1;
        var r = toExclusive + rootLength - 1;

        while (l < r)
        {
            if ((l & 1) == 0)
                leftResult = Operate(leftResult, tree[l]);
            if ((r & 1) == 0)
                rightResult = Operate(tree[r - 1], rightResult);
            l /= 2;
            r = (r - 1) / 2;
        }

        return Operate(leftResult, rightResult);
    }


    [System.Diagnostics.DebuggerDisplay("{" + nameof(value) + "}", Name = "{" + nameof(key) + "}")]
    internal struct KeyValuePairs
    {
        private string key;
        private int value;

        public KeyValuePairs(string key, int value)
        {
            this.key = key;
            this.value = value;
        }
    }
    class SegmentTreeDebugView
    {
        private SegmentTree segmentTree;
        public SegmentTreeDebugView(SegmentTree segmentTree)
        {
            this.segmentTree = segmentTree;
        }

        [System.Diagnostics.DebuggerBrowsable(System.Diagnostics.DebuggerBrowsableState.RootHidden)]
        public KeyValuePairs[] Tree
        {
            get
            {
                var keys = new List<KeyValuePairs>(segmentTree.tree.Length);
                for (var len = segmentTree.rootLength; len > 0; len >>= 1)
                {
                    var unit = segmentTree.rootLength / len;
                    for (var i = 0; i < len; i++)
                    {
                        var index = i + len - 1;
                        if (unit == 1)
                            keys.Add(new KeyValuePairs($"{i}", segmentTree.tree[index]));
                        else
                        {
                            var from = i * unit;
                            keys.Add(new KeyValuePairs($"[{from}-{from + unit})", segmentTree.tree[index]));
                        }
                    }
                }
                return keys.ToArray();
            }
        }
    }
}


Measured memory_bytes: 26028