#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int INF = (int) 1e9 + 1e6 + 123;
const ll LINF = (ll) 1e18 + 1e9 + 123;
#define rep(i, s, t) for (auto i = (s); i < (t); ++(i))
#define per(i, s, t) for (auto i = (s); i >= (t); --(i))
#define sz(x) ((int)(x).size())
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
bool mini(auto &x, const auto &y) {
if (y < x) {
x = y;
return 1;
}
return 0;
}
bool maxi(auto &x, const auto &y) {
if (y > x) {
x = y;
return 1;
}
return 0;
}
void run();
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
run();
return 0;
}
const int N = (int) 1e6 + 123;
const ll MOD = (ll) 1e9 + 7;
int n;
int a[N], b[N];
vector<int> adj[N], g[N];
int col[N];
int p[N];
int cnt[N];
void dfs(int v, int cc = 1) {
col[v] = cc;
for (int u : g[v]) {
if (!col[u]) {
dfs(u, 3 - cc);
}
if (col[u] != 3 - cc) {
cout << "0\n";
exit(0);
}
}
}
int get(int v) {
return (p[v] == v ? v : (p[v] = get(p[v])));
}
void unite(int u, int v) {
u = get(u);
v = get(v);
if (u != v) {
p[u] = v;
cnt[v] += cnt[u];
}
}
bool closed[N];
pair<int, bool> what[2 * N];
int L[N], R[N];
void run() {
rep(i, 0, N) p[i] = i, cnt[i] = 1;
cin >> n;
rep(i, 0, n) {
cin >> a[i] >> b[i];
a[i]--;
b[i]--;
what[a[i]] = {i, 0};
what[b[i]] = {i, 1};
}
{
set<int> q;
rep(i, 0, 2 * n) {
if (what[i].second) {
continue;
}
int v = what[i].first;
auto it = q.insert(b[v]).first;
if (it != q.begin()) {
--it;
R[v] = *it;
} else {
R[v] = -1;
}
}
}
{
set<int> q;
per(i, 2 * n - 1, 0) {
if (!what[i].second) {
continue;
}
int v = what[i].first;
auto it = q.insert(a[v]).first;
++it;
if (it != q.end()) {
L[v] = *it;
} else {
L[v] = INF;
}
}
}
rep(i, 0, n) {
if (L[i] < R[i]) {
cout << "0\n";
return;
}
}
vector<int> st, tmp;
rep(i, 0, 2 * n) {
int v = what[i].first;
if (what[i].second) {
while (1) {
while (cnt[st.back()] == 0) {
st.pop_back();
}
int t = st.back();
if (t == get(v)) {
break;
}
st.pop_back();
if (cnt[t]) {
tmp.pb(t);
}
}
if (sz(tmp)) {
rep(i, 1, sz(tmp)) {
unite(tmp[0], tmp[i]);
}
int u = get(tmp[0]);
adj[v].pb(u);
adj[u].pb(v);
st.pb(u);
tmp.clear();
}
cnt[get(v)]--;
} else {
st.pb(v);
}
}
rep(v, 0, n) {
for (int u : adj[v]) {
g[get(v)].pb(get(u));
}
}
ll ans = 1;
rep(i, 0, n) {
if (get(i) == i && !col[i]) {
dfs(i);
ans = (ans * 2) % MOD;
}
}
cout << ans << "\n";
}
