#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;

// template {{{  0 
// using {{{ 1
using ll = long long int;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vii = vector<pii>;
using vll = vector<pll>;
// }}} 1
// definition {{{ 1
// scaning {{{ 2
#define Scd(x) scanf("%d", &x)
#define Scd2(x,y) scanf("%d%d", &x, &y)
#define Scd3(x,y,z) scanf("%d%d%d", &x, &y, &z)
#define Scll(x) scanf("%lld", &x)
#define Scll2(x,y) scanf("%lld%lld", &x, &y)
#define Scll3(x,y,z) scanf("%lld%lld%lld", &x, &y, &z)
#define Scc(c) scanf("%c", &c);
#define Scs(s) scanf("%s", s);
#define Scstr(s) scanf("%s", &s);
// }}} 2
// constants {{{ 2
#define EPS (1e-7)
#define INF (2e9)
#define PI (acos(-1))
// }}} 2
// systems {{{ 2
#define Repe(x,y,z) for(ll x = z; x < y; x++)
#define Rep(x,y) Repe(x,y,0)
#define RRepe(x,y,z) for(ll x = y-z-1; x >= 0; x--)
#define RRep(x,y) RRepe(x,y,0)
// }}} 2
// output {{{ 2
#define YesNo(a) (a)?printf("Yes\n"):printf("No\n")
#define YESNO(a) (a)?printf("YES\n"):printf("NO\n")
// }}} 2
// }}} 1
// input {{{ 1
// }}} 1
// }}} 0

const long long int mod = 998244353;

// PowMod( base, index, modulo) return base ** index % modulo {{{
// PowMod = base ** index % mod ( natural numbers )
inline constexpr long long int PowMod( long long int base, long long int index, long long int modulo = mod ){
    if( index == 0 ) return 1;
    // O( log(index) )
    if( index % 2 ){
        return base * PowMod(base, index - 1, modulo) % modulo;
    }else{
        long long int Phalf = index / 2;
        long long int half = PowMod(base, Phalf, modulo);
        return half * half % modulo;
    }
}
// }}}
// CombMod( n, r, modulo ) return nCr % modulo {{{
// CombMod(ination) = nCr % mod ( natural number )
inline constexpr long long int CombMod( long long int n, long long int r, long long int modulo = mod){
    if( n < r ) return CombMod(r,n,modulo);
    long long int Upper = 1;
    long long int Lower = 1;
    for(long long int i = 0; i < r; i++){
        Upper = Upper * (n-i) % modulo;
        Lower = Lower * (i+1) % modulo;
    }
    // Return (Upper / Lower)
    long long int ret = Upper * PowMod(Lower,modulo-2,modulo) % modulo;
    return ret;
}
// }}}
// FactMod( n, modulo ) return n! % modulo {{{
// Fact(orial) = n! % mod ( natural number )
inline constexpr long long int Fact( long long int n, long long int modulo = mod){
    long long int Upper = 1;
    for(long long int i = 0; i < n; i++){
        Upper = Upper * (n-i) % modulo;
    }
    return Upper;
}
// }}}
// modint {{{

struct modint{
    long long int a;
    inline constexpr modint( long long int x = 0 ) noexcept : a(x % mod) {}
    inline constexpr long long int &value() noexcept { return a; }
    inline constexpr const long long int &value() const noexcept { return a; }
    inline constexpr modint operator+(const modint rhs) const noexcept{ return modint(*this) += rhs; }
    inline constexpr modint operator+(const int rhs) const noexcept{ return modint(*this) += rhs; }
    inline constexpr modint operator+(const long long int rhs) const noexcept{ return modint(*this) += rhs; }
    inline constexpr modint operator-(const modint rhs) const noexcept{ return modint(*this) -= rhs; }
    inline constexpr modint operator-(const int rhs) const noexcept{ return modint(*this) -= rhs; }
    inline constexpr modint operator-(const long long int rhs) const noexcept{ return modint(*this) -= rhs; }
    inline constexpr modint operator*(const modint rhs) const noexcept{ return modint(*this) *= rhs; }
    inline constexpr modint operator*(const int rhs) const noexcept{ return modint(*this) *= rhs; }
    inline constexpr modint operator*(const long long int rhs) const noexcept{ return modint(*this) *= rhs; }
    inline constexpr modint operator/(const modint rhs) const noexcept{ return modint(*this) /= rhs; }
    inline constexpr modint operator/(const int rhs) const noexcept{ return modint(*this) /= rhs; }
    inline constexpr modint operator/(const long long int rhs) const noexcept{ return modint(*this) /= rhs; }
    inline constexpr modint operator+=(const modint rhs) noexcept{ a += rhs.a; if( a >= mod ) a -= mod; return *this; }
    inline constexpr modint operator-=(const modint rhs) noexcept{ a -= rhs.a; if( a < 0 ) a += mod; return *this; }
    inline constexpr modint operator*=(const modint rhs) noexcept{ a = a * rhs.a % mod ;  return *this; }
    inline constexpr modint operator/=(const modint rhs) noexcept{ a = a * PowMod(rhs.a,mod-2) % mod; return *this; }
};

// }}}

// {{{ Segment Tree

// T : 要素
template <typename T>
struct SegmentTree{

    int leng;
    using F = function<T(T,T)>;
    F f;  // T*T -> T
    T ti; // (T,f) の 単位元
    vector<T> data; // 1-indexed

    SegmentTree( F f, T ti ) :
        f(f),ti(ti){}

    void init( int n ){
        leng = 1;
        while( leng < n ) leng += leng;
        data.assign(leng*2,ti);
    }

    void build( vector<T> &v ){
        int n = v.size();
        init( n );
        for (int i = 0; i < n; i++) data[leng+i] = v[i];
        for (int i = leng-1; i > 0 ; i--)
            data[i] = f(data[i<<1],data[(i<<1)|1] );
    }

    // data[a] を x で 変更
    void upda( int a, T x ){

        a += leng;

        data[a] = x;

        while( a >>= 1 ){
            data[a] = f( data[a<<1] , data[(a<<1)|1] );
        }

    }

    // [a,b)の f(演算結果) を求める
    T query(int a, int b, int k = 1, int l = 0, int r = -1 ){

        if( r == -1 ) return query(a,b,k,l,leng);

        //今探すkでの範囲がオーバーしたら単位元をを返す
        if( a>=r || b<=l ) return ti;

        //範囲内ならそのまま返す
        else if( a<=l && b>=r ){
            return data[k];
        //そうでもないなら子へ
        }else{
            T ld = query(a,b,k<<1,l,(l+r)/2);
            T rd = query(a,b,(k<<1)|1,(l+r)/2,r);
            return f(ld,rd);
        }

    }
    
    void dump(){
        for( int i = 1; i < leng*2; i++ ){
            cerr << "d[" << i << "]=" << data[i] << endl;
        }
    }
    
};

// }}}

int main() {

    int N;
    Scd(N);
    vii a(N);
    map<int,int> id;
    Rep(i,N){
        Scd2(a[i].first,a[i].second);
    }

    sort(a.begin(),a.end());

    Rep(i,N){
        id[a[i].first] = i;
    }

    auto f = []( int a, int b ){ return max(a,b); };
    SegmentTree<int> tom( f,0 );
    vi to(N,N-1);
    Rep(i,N){
        auto it = --id.upper_bound(a[i].first+a[i].second-1);
        if( it == id.end() ) continue;
        to[i] = it->second;
    }

    tom.build( to );

    RRep(i,N){
        // max([i,toa]) > to[i] => to[i] = max
        int from = i;
        int toa = tom.query(from,to[from]+1);
        while( toa > from ){
            from = toa;
            toa = tom.query(from,to[from]+1);
        }
        tom.upda(i,toa);
        to[i] = toa;
    }

//     Rep(i,N){
//         printf ("%lld(%d,%d) %lld->%d\n", i, a[i].first, a[i].second, i, to[i] );
//     }
//
    vector<modint> dp(N+1,0);
    dp[0] = 1;
    Rep(i,N){
        dp[i+1] += dp[i];
        dp[to[i]+1] += dp[i];
    }

    printf ("%lld\n", dp[N] );

    return 0;
}



Measured memory_bytes: 15616