#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
using ll = long long;
using ld = long double;
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define sz(x) (int)x.size()
#define endl '\n'
const int mod = 1e9 + 7;
const int inf = 2e9 + 5;
const ll linf = 9e18 + 5;
int n;
const int N = 1e6 + 5;
const int L = (1 << 21);
int seg[L << 1][2];
int arr[2 * N];
int a[N];
int b[N];
bool mark[N];
bool color[N];
void cre() {
for (int ind = L; ind < (L << 1); ind++) {
seg[ind][0] = -1;
seg[ind][1] = 2 * n;
}
for (int i = 1; i <= n; i++) {
seg[a[i] + L][0] = b[i];
seg[b[i] + L][1] = a[i];
}
for (int ind = L - 1; ind >= 1; ind--) {
seg[ind][0] = max(seg[ind << 1][0], seg[ind << 1 | 1][0]);
seg[ind][1] = min(seg[ind << 1][1], seg[ind << 1 | 1][1]);
}
}
void rem(int x) {
int ind;
ind = a[x] + L;
seg[ind][0] = -1;
ind >>= 1;
while (ind) {
seg[ind][0] = max(seg[ind << 1][0], seg[ind << 1 | 1][0]);
ind >>= 1;
}
ind = b[x] + L;
seg[ind][1] = 2 * n;
ind >>= 1;
while (ind) {
seg[ind][1] = min(seg[ind << 1][1], seg[ind << 1 | 1][1]);
ind >>= 1;
}
}
pair<int, int> get(int b, int e) {
e++;
b += L;
e += L;
pair<int, int> ans = mp(-1, 2 * n);
while (b != e) {
if (b & 1) {
ans.fi = max(ans.fi, seg[b][0]);
ans.se = min(ans.se, seg[b][1]);
b++;
}
if (e & 1) {
e--;
ans.fi = max(ans.fi, seg[e][0]);
ans.se = min(ans.se, seg[e][1]);
}
b >>= 1;
e >>= 1;
}
return ans;
}
void init() {
}
void input() {
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i] >> b[i];
a[i]--;
b[i]--;
arr[a[i]] = i;
arr[b[i]] = i;
}
}
void dfs(int u) {
if (!u) {
throw;
}
rem(u);
mark[u] = true;
while (true) {
int val = get(a[u], b[u]).fi;
if (val == -1 || val < b[u]) {
break;
}
int v = arr[val];
color[v] = !color[u];
dfs(v);
}
while (true) {
int val = get(a[u], b[u]).se;
if (val == 2 * n || val > a[u]) {
break;
}
int v = arr[val];
color[v] = !color[u];
dfs(v);
}
}
void solve() {
cre();
int ans = 1;
for (int i = 1; i <= n; i++) {
if (!mark[i]) {
dfs(i);
ans = (2 * ans) % mod;
}
}
vector<int> v;
for (int i = 0; i < 2 * n; i++) {
int ind = arr[i];
if (color[ind]) {
continue;
}
if (b[ind] == i) {
if (v.back() != ind) {
cout << 0;
return;
}
v.pop_back();
}
else {
v.pb(ind);
}
}
for (int i = 0; i < 2 * n; i++) {
int ind = arr[i];
if (!color[ind]) {
continue;
}
if (b[ind] == i) {
if (v.back() != ind) {
cout << 0;
return;
}
v.pop_back();
}
else {
v.pb(ind);
}
}
cout << ans;
}
void output() {
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int number_of_testcases = 1;
//cin >> number_of_testcases;
while (number_of_testcases--) {
init();
input();
solve();
output();
}
return 0;
}
