#include <bits/stdc++.h>
using i64 = long long;
constexpr int P = 1E9 + 7;
constexpr int N = 2E6 + 5;
struct Info {
int mn;
int mx;
Info(int x = N, int y = -1) : mn(x), mx(y) {}
};
Info operator+(const Info &a, const Info &b) {
Info c;
c.mn = std::min(a.mn, b.mn);
c.mx = std::max(a.mx, b.mx);
return c;
}
struct SegmentTree {
int n;
std::vector<Info> t;
SegmentTree(int n) : n(n), t(4 * n) {}
void modify(int p, int l, int r, int x, Info y) {
if (l == r - 1) {
t[p] = y;
} else {
int m = (l + r) / 2;
if (x < m) {
modify(2 * p, l, m, x, y);
} else {
modify(2 * p + 1, m, r, x, y);
}
t[p] = t[2 * p] + t[2 * p + 1];
}
}
void modify(int x, int y) {
modify(1, 0, n, x, Info(y, y));
}
void remove(int x) {
modify(1, 0, n, x, Info());
}
Info query(int p, int l, int r, int x, int y) {
if (r <= x || y <= l) {
return Info();
}
if (x <= l && r <= y) {
return t[p];
}
int m = (l + r) / 2;
return query(2 * p, l, m, x, y) + query(2 * p + 1, m, r, x, y);
}
Info query(int l, int r) {
return query(1, 0, n, l, r);
}
};
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(NULL);
int n;
std::cin >> n;
std::vector<int> a(n), b(n);
std::vector<int> p(2 * n), id(2 * n);
for (int i = 0; i < n; i++) {
std::cin >> a[i] >> b[i];
a[i]--;
b[i]--;
p[a[i]] = b[i];
p[b[i]] = a[i];
id[a[i]] = id[b[i]] = i;
}
std::vector<bool> vis(n);
std::vector<int> color(n);
vis.assign(n, false);
SegmentTree s(2 * n);
for (int i = 0; i < 2 * n; i++) {
s.modify(i, p[i]);
}
int c = 0;
for (int i = 0; i < n; i++) {
if (!vis[i]) {
c++;
std::function<void(int)> dfs = [&](int u) {
vis[u] = true;
s.remove(a[u]);
s.remove(b[u]);
while (true) {
Info x = s.query(a[u], b[u]);
if (x.mn < a[u]) {
color[id[x.mn]] = color[u] ^ 1;
dfs(id[x.mn]);
} else if (x.mx > b[u]) {
color[id[x.mx]] = color[u] ^ 1;
dfs(id[x.mx]);
} else {
break;
}
}
};
dfs(i);
}
}
std::stack<int> st[2];
for (int i = 0; i < 2 * n; i++) {
if (p[i] > i) {
st[color[id[i]]].push(id[i]);
} else {
if (st[color[id[i]]].top() != id[i]) {
std::cout << "0\n";
return 0;
}
st[color[id[i]]].pop();
}
}
int ans = 1;
for (int i = 0; i < c; i++) {
ans = 2 * ans % P;
}
std::cout << ans << "\n";
return 0;
}
