#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2e6 + 10, mod = 1e9 + 7;
int n, ans = 1, a[MAXN], b[MAXN], seen[MAXN], ind[MAXN], seg1[4 * MAXN], seg2[4 * MAXN];
bool is[MAXN];
vector<int> s1, s2;
void make1(int u, int l, int r) {
seg1[u] = -1;
if (r - l == 1)
return;
int mid = (l + r) / 2;
make1(2 * u, l, mid);
make1(2 * u + 1, mid, r);
}
void make2(int u, int l, int r) {
seg2[u] = MAXN;
if (r - l == 1)
return;
int mid = (l + r) / 2;
make2(2 * u, l, mid);
make2(2 * u + 1, mid, r);
}
void upd1(int u, int l, int r, int i, int x) {
if (i < l || i >= r)
return;
if (r - l == 1) {
seg1[u] = x;
return;
}
int mid = (l + r) / 2;
upd1(2 * u, l, mid, i, x);
upd1(2 * u + 1, mid, r, i, x);
seg1[u] = max(seg1[2 * u], seg1[2 * u + 1]);
}
void upd2(int u, int l, int r, int i, int x) {
if (i < l || i >= r)
return;
if (r - l == 1) {
seg2[u] = x;
return;
}
int mid = (l + r) / 2;
upd2(2 * u, l, mid, i, x);
upd2(2 * u + 1, mid, r, i, x);
seg2[u] = min(seg2[2 * u], seg2[2 * u + 1]);
}
int get1(int u, int l, int r, int s, int e) {
if (s <= l && r <= e)
return seg1[u];
if (e <= l || r <= s)
return -1;
int mid = (l + r) / 2;
return max(get1(2 * u, l, mid, s, e), get1(2 * u + 1, mid, r, s, e));
}
int get2(int u, int l, int r, int s, int e) {
if (s <= l && r <= e)
return seg2[u];
if (e <= l || r <= s)
return MAXN;
int mid = (l + r) / 2;
return min(get2(2 * u, l, mid, s, e), get2(2 * u + 1, mid, r, s, e));
}
void input() {
cin >> n;
for (int i = 1; i <= 2 * n; i++)
ind[i] = -1;
make1(1, 1, 2 * n + 1);
make2(1, 1, 2 * n + 1);
for (int i = 0; i < n; i++) {
cin >> a[i] >> b[i];
ind[a[i]] = ind[b[i]] = i;
is[a[i]] = true;
upd1(1, 1, 2 * n + 1, a[i], b[i]);
upd2(1, 1, 2 * n + 1, b[i], a[i]);
}
}
void dfs(int u) {
upd1(1, 1, 2 * n + 1, a[u], -1);
upd2(1, 1, 2 * n + 1, b[u], MAXN);
int x = get1(1, 1, 2 * n + 1, a[u], b[u]);
while (x > b[u]) {
int v = ind[x];
seen[v] = 3 - seen[u];
dfs(v);
x = get1(1, 1, 2 * n + 1, a[u], b[u]);
}
x = get2(1, 1, 2 * n + 1, a[u], b[u]);
while (x < a[u]) {
int v = ind[x];
seen[v] = 3 - seen[u];
dfs(v);
x = get2(1, 1, 2 * n + 1, a[u], b[u]);
}
}
void findAns() {
for (int i = 0; i < n; i++)
if (!seen[i]) {
seen[i] = 1;
dfs(i);
ans = (ans * 2) % mod;
}
}
bool check() {
for (int i = 1; i <= 2 * n; i++) {
if (ind[i] == -1)
continue;
if (is[i]) {
if (seen[ind[i]] == 1)
s1.push_back(ind[i]);
else
s2.push_back(ind[i]);
}
else {
if (seen[ind[i]] == 1) {
if (s1.empty() || s1.back() != ind[i])
return true;
s1.pop_back();
}
else {
if (s2.empty() || s2.back() != ind[i])
return true;
s2.pop_back();
}
}
}
return false;
}
int main() {
ios::sync_with_stdio(false); cin.tie(0);
input();
findAns();
cout << (check()? 0: ans) << endl;
return 0;
}
