#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define MOD 998244353
#define INF (1LL<<57)
#define MV 200001
#define LMV 21
#define ff first
#define ss second
#define pb push_back
#define eb emplace_back
#define emp emplace
#define whoami(x) cerr<<#x<<" "<<x<<"\n";
#define mp make_pair
#define ins insert
#define sz size

void FLASH() {ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);}
void SETF() {cout.ios_base::setf(ios_base::fixed);}
void UNSETF() {cout.ios_base::unsetf(ios_base::fixed);}

typedef long long ll;
typedef long double ld;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;
typedef pair<PII, int> PPII;
typedef pair<PLL, ll> PPLL;
typedef map<int, int> MII;

template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template <typename T>
using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;

struct h_llint {
  static uint64_t splitmix64(uint64_t x) {    // http://xorshift.di.unimi.it/splitmix64.c
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};

struct h_pair{
  size_t operator()(const PLL&x)const{
    return hash<ll>()(((ll)x.ff)^(((ll)x.ss)<<32));
  }
};

typedef map<ll, ll> MLL;
typedef map<PII, int> MPII;
typedef map<PLL, ll> MPLL;
typedef set<int> SI;
typedef set<ll> SL;
//ordered_set = order_by_key(.)
//ordered_set = find_by_order(.)
typedef ordered_set<int> OSI;
typedef ordered_set<ll> OSL;
typedef ordered_multiset<int> MOSI;
typedef ordered_multiset<ll> MOSL;
typedef unordered_map<ll, int, h_llint> UMLI;
typedef unordered_map<ll, ll, h_llint> UMLL;
typedef unordered_map<PLL, int, h_pair> UMPI;
typedef unordered_map<PLL, ll, h_pair> UMPL;

int ar[MV], seg[4*MV];
ll arr[MV], memo[MV];
PLL xz[MV];

int bs2(int s, int n)
{
	int lo = s;
	int hi = n;
	while(lo < hi)
	{
		int mid = lo + (hi - lo + 1)/2;
		if(xz[s].ss >= xz[mid].ff)
		lo = mid;
		else hi = mid - 1;	
	}
	return lo;
}

class segtree
{
	public: void build(int i,int s, int d);
			int merger(int left, int right);
			void update(int i, int s, int d, int x, int v);
			int query(int i, int s, int d, int qs, int qd);
};

void segtree::build(int i, int s, int d)
{
	if(s == d)
	{
		seg[i] = ar[s];
		return;
	}	
	int m = (s + d)/2;
	build(2*i, s, m);
	build(2*i+1, m+1, d);
	seg[i] = merger(seg[2*i], seg[2*i+1]);
	return;
}

int segtree::merger(int left, int right)
{
	return max(left, right);
}

void segtree::update(int i, int s, int d, int x, int v)
{
	if(s == d)
	{
		seg[i] = v;
		return;
	}
	int m = (s + d)/2;
	if(x <= m)
	update(2*i, s, m, x, v);
	else update(2*i+1, m+1, d, x, v);
	seg[i] = merger(seg[2*i], seg[2*i+1]);
	return;	
}

int segtree::query(int i, int s, int d, int qs, int qd)
{
	if(qs > d || qd < s)
	return 0;
	else if(qs <= s && d <= qd)
	return seg[i];
	int m = (s + d)/2;
	int p1 = query(2*i, s, m, qs, qd);
	int p2 = query(2*i+1, m+1, d, qs, qd);
	return merger(p1, p2);	
}

ll xd(int ix, ll n)
{
	if(ix == n+1)
	return 1;
	if(memo[ix] != -1)
	return memo[ix];
	ll ans = 0;
	ans = ((ans%MOD) + (xd(ix+1, n)%MOD))%MOD;
	ans = ((ans%MOD) + (xd(ar[ix]+1, n)%MOD))%MOD;
	memo[ix] = ans;
	return ans;
}

void solve(int T)
{
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>xz[i].ff>>xz[i].ss;
		xz[i].ss = xz[i].ff + xz[i].ss - 1;
	}	
	sort(xz+1, xz+n+1, [](PLL A, PLL B){ return ((A.ff < B.ff) || ((A.ff == B.ff) && (A.ss < B.ss))); });
	iota(ar, ar+n+1, 0);
	memset(memo, -1, sizeof(memo));
	segtree D;
	D.build(1, 1, n);
	D.update(1, 1, n, n, n);
	for(int i=n;i>0;i--)
	{
		int ft = bs2(i, n);
		ar[i] = D.query(1, 1, n, i, ft);
		D.update(1, 1, n, i, ar[i]);
	}	
	int ans = xd(1, n)%MOD;
	cout<<ans<<"\n";
	return;
}

int main(void)
{
	FLASH();
	int T;
	T = 1;

// #ifndef ONLINE_JUDGE
// 	time_t time_t1, time_t2;
// 	time_t1 = clock();
// #endif

	while(T--)
	solve(T);

// #ifndef ONLINE_JUDGE
// 	time_t2 = clock();
// 	SETF();
// 	cout<<"Time taken: "<<setprecision(7)<<(time_t2 - time_t1)/(double)CLOCKS_PER_SEC<<"\n";
// 	UNSETF();
// #endif

	return 0;
}

Measured memory_bytes: 15616