#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using vi = vector<int>;
using vll = vector<ll>;
using vii = vector<ii>;
const ll MOD = 998244353;
const int INF = 1e9+9;
const int MAXN = 1000006;
template <class T, class Oper>
struct LzySegTree {
int n, h; vector<T> st;
Oper op;
LzySegTree(const vector<T> &A)
: n(A.size()), h(sizeof(int)*8-__builtin_clz(n)),
st(n<<1), op(*this) {
copy(A.begin(), A.end(), st.begin()+n);
build(0, n);
}
void build(int L, int R) {
int len = 2;
for (L += n, R += n-1; L > 1; len <<= 1) {
L >>= 1, R >>= 1;
for (int i = R; i >= L; --i) op.calc(i, len);
}
}
void push(int L, int R) {
int s = h, len = 1<<h;
for (L += n, R += n-1; s > 0; --s, len >>= 1)
for (int i = L >> s; i <= R >> s; ++i) op.pushDelOps(i, len);
}
void update(int L, int R, typename Oper::TUpd val) {
push(L, L+1), push(R-1, R);
int L0 = L, R0 = R, len = 1;
for (L += n, R += n; L < R; L >>= 1, R >>= 1, len <<= 1) {
if (L&1) op.updateOp(L++, len, val);
if (R&1) op.updateOp(--R, len, val);
}
build(L0, L0+1), build(R0-1, R0);
}
T query(int L, int R) {
push(L, L+1), push(R-1, R);
T resl = op.identity, resr = op.identity;
for (L += n, R += n; L < R; L >>= 1, R >>= 1) {
if (L&1) resl = op.op(resl, st[L++]);
if (R&1) resr = op.op(st[--R], resr);
}
return op.op(resl, resr);
}
void print() {
for (int i = 0; i < n; ++i) {
cerr << i << ": " << st[i] << " d(" << op.d[i] << endl;
}
for (int i = n; i < 2*n; ++i) {
cerr << i << ": " << st[i] << endl;
}
}
};
template<int N>
struct GetSetEqClass {
const int identity = 0;
using TUpd = int;
LzySegTree<int, GetSetEqClass> &st; vector<int> d;
GetSetEqClass(LzySegTree<int, GetSetEqClass> &st) : st(st), d(st.n, -1) {}
static inline int op(int a, int b) {
if (!a) return b;
if (!b) return a;
return a != b? N+1 : a;
}
inline void calc(int p, int len) {
st.st[p] = d[p] == -1? op(st.st[p<<1], st.st[p<<1|1]) : d[p];
}
inline void updateOp(int p, int len, int value) {
if (value == -1) return;
st.st[p] = value;
if (p < st.n) d[p] = value;
}
inline void pushDelOps(int p, int len) {
updateOp(p<<1, len>>1, d[p]);
updateOp(p<<1|1, len>>1, d[p]);
d[p] = -1;
}
};
int n, a[MAXN], b[MAXN], e[MAXN], id[MAXN];
int main () {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> a[i] >> b[i]; --a[i], --b[i];
e[a[i]] = -i;
e[b[i]] = i;
}
LzySegTree<int, GetSetEqClass<2>> lst(vi(2*n));
ll ans = 1;
vi stack;
for (int i = 0; i < 2*n; ++i) {
// cerr << "stack\n";
// for (int v : stack) {
// cerr << v << " ";
// }
// cerr << endl;
if (e[i] < 0) {
id[-e[i]] = stack.size();
stack.push_back(-e[i]);
} else {
int val = lst.query(id[e[i]]+1, stack.size());
int cur = lst.query(id[e[i]], id[e[i]]+1);
// cerr << a[e[i]] << " " << b[e[i]] << ") ";
// cerr << cur << " " << val << endl;
if (val == 0) {
lst.update(id[e[i]], id[e[i]]+1, 0);
if (cur == 0) {
lst.update(id[e[i]]+1, stack.size(), 1);
ans *= 2;
if (ans > MOD) ans -= MOD;
} else {
lst.update(id[e[i]]+1, stack.size(), cur == 1? 2 : 1);
}
} else if (val == 3 or val == lst.query(id[e[i]], id[e[i]]+1)) {
ans = 0;
} else {
lst.update(id[e[i]]+1, stack.size(), val);
lst.update(id[e[i]], id[e[i]]+1, 0);
}
}
while(!stack.empty() and b[stack.back()] <= i) stack.pop_back();
}
cout << ans << endl;
}
