#include <algorithm>
#include <iostream>
#include <cassert>
#include <vector>
#include <set>
#include <queue>
#define SZ(x) ((int) (x).size())
using namespace std;
typedef long long i64;
const int MOD = (int) 1e9 + 7;
struct Segment {
int l, r;
Segment() = default;
Segment(int _l, int _r):
l(_l), r(_r) {}
};
class DSU {
public:
DSU(int n): f(vector<int>(n)) {
for (int i = 0; i < n; ++i) {
f[i] = i;
}
}
int& operator[](int x) {
int y, p;
for (y = x; y != f[y]; y = f[y]);
for (; x != y; x = p) {
p = f[x];
f[x] = y;
}
return f[y];
}
private:
vector<int> f;
};
int main() {
#ifdef LOCAL_RUN
freopen("task.in", "r", stdin);
freopen("task.out", "w", stdout);
//freopen("task.err", "w", stderr);
#endif // ONLINE_JUDGE
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
vector<Segment> a(n + 1);
vector<int> event(2 * n + 1);
for (int i = 1; i <= n; ++i) {
cin >> a[i].l >> a[i].r;
event[a[i].l] = i;
event[a[i].r] = -i;
}
DSU f(n + 1);
vector<int> before(n + 1, -1), last(n + 1, -1);
for (int i = 1; i <= n; ++i) {
last[i] = i;
}
vector<bool> erased(n + 1, false);
vector<int> stk;
vector<vector<int>> diffGraph(n + 1);
for (int i = 1; i <= 2 * n; ++i) {
if (event[i] > 0) {
int e = event[i];
stk.push_back(e);
} else {
int e = -event[i];
if (before[e] != -1) {
if (!erased[before[e]]) {
cout << "0\n";
return 0;
}
}
int xp = f[e];
if (stk.back() == xp) {
if (e == xp) {
stk.pop_back();
}
} else {
int prev = -1;
while (!stk.empty() && stk.back() != xp) {
int x = stk.back();
stk.pop_back();
if (prev == -1) {
before[last[x]] = -1;
} else {
before[last[x]] = prev;
last[x] = last[prev];
f[prev] = x;
}
prev = x;
}
if (e == xp) {
stk.pop_back();
}
stk.push_back(prev);
diffGraph[prev].push_back(e);
diffGraph[e].push_back(prev);
}
erased[e] = true;
}
}
vector<vector<int>> graph(n + 1);
for (int i = 1; i <= n; ++i) {
for (int to: diffGraph[i]) {
graph[f[i]].push_back(f[to]);
}
}
vector<bool> used(n + 1, false);
vector<int> color(n + 1);
int cnt = 0;
for (int i = 1; i <= n; ++i) {
if (!used[i] && f[i] == i) {
queue<int> q;
q.push(i);
used[i] = true;
color[i] = 0;
while (!q.empty()) {
int node = q.front();
q.pop();
for (int to: graph[node]) {
if (!used[to]) {
used[to] = true;
color[to] = color[node] ^ 1;
q.push(to);
}
}
}
cnt++;
}
}
for (int i = 1; i <= n; ++i) {
if (f[i] != i) continue;
for (int to: graph[i]) {
if (color[i] == color[to]) {
cnt = -1;
}
}
}
if (cnt == -1) {
cout << "0\n";
} else {
int ans = 1;
for (int i = 0; i < cnt; ++i) {
ans = (ans + ans) % MOD;
}
cout << ans << '\n';
}
}
