#include <iostream>
#include <vector>
#include <array>
#include <map>
#define ll long long
using namespace std;
ll n, s, f = 1, X[1000000], F[1000000], M = 1e9 + 7;
vector <ll> V, U, adj[1000000];
map <ll, ll> mp;
bool B[1000000];
array <ll, 2> A[1000000], R[1000000];
void dfs(ll u, ll w) {
F[u] = w;
for (auto v : adj[u]) {
if (F[v] == -1) {
dfs(v, w^1);
}
else if (F[u] == F[v]) {
cout << "0\n";
exit(0);
}
}
}
int main() {
cin.tie(0);
ios::sync_with_stdio(0);
cin >> n;
for (int i=0; i<n; ++i) {
F[i] = -1;
cin >> R[i][0] >> R[i][1];
--R[i][0], --R[i][1];
A[R[i][0]] = {i, 0}, A[R[i][1]] = {i, 1};
}
for (int i=0; i<2*n; ++i) {
if (!A[i][1]) {
X[A[i][0]] = -1e18;
auto it = mp.lower_bound(R[A[i][0]][1]);
if (it != mp.begin()) {
it = prev(it);
X[A[i][0]] = it->first;
}
++mp[R[A[i][0]][1]];
}
}
mp.clear();
for (int i=2*n-1; i>=0; --i) {
if (A[i][1]) {
auto it = mp.lower_bound(R[A[i][0]][0]);
if (it != mp.end() && it->first < X[A[i][0]]) {
cout << "0\n";
return 0;
}
++mp[R[A[i][0]][0]];
}
}
for (int i=0; i<2*n; ++i) {
if (A[i][1]) {
B[A[i][0]] = 1;
while (!V.empty()) {
auto u = V.back();
if (R[u][0] < R[A[i][0]][0]) break;
V.pop_back();
if (!B[u]) {
//cout << u << " " << A[i][0] << endl;
U.push_back(u);
adj[u].push_back(A[i][0]);
adj[A[i][0]].push_back(u);
}
}
while (!U.empty()) {
auto u = U.back();
U.pop_back();
V.push_back(u);
}
}
else V.push_back(A[i][0]);
}
for (int i=0; i<n; ++i) {
if (F[i] == -1) {
f *= 2;
f %= M;
dfs(i, 0);
}
}
cout << f << '\n';
}
