// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>
using namespace std;
#define nl '\n'
#define f first
#define s second
#define mp make_pair
using ll = long long;
using pi = pair<int, int>;
template<class T> using V = vector<T>;
using vi = V<int>;
struct DSU {
vi e; V<set<pi>> S; void init(int N) { e = vi(N, -1); S = V<set<pi>>(N); }
int get(int x) { return e[x] < 0 ? x : e[x] = get(e[x]); }
void ins(int x, pi v) { x = get(x); S[x].insert(v); }
void erase(int x, pi v) { x = get(x); assert(S[x].find(v) != S[x].end()); S[x].erase(v); }
int siz(int x) { return size(S[get(x)]); }
pi top(int x) { return *begin(S[get(x)]); }
pi top2(int x) { return *next(begin(S[get(x)])); }
bool unite(int x, int y) {
x = get(x), y = get(y); if (x == y) return 0;
// assert(x != y);
if (e[x] > e[y]) swap(x, y);
for(auto& v : S[y]) S[x].insert(v);
e[x] += e[y]; e[y] = x; return 1;
}
};
int main() {
cin.tie(0)->sync_with_stdio(0);
int N; cin >> N;
V<pi> E(2*N);
vi A(N), B(N); for(int i = 0; i < N; i++) {
cin >> A[i] >> B[i]; --A[i], --B[i];
E[A[i]] = mp(i, +1);
E[B[i]] = mp(i, -1);
}
V<vi> adj(N);
auto ae = [&](int u, int v) {
// cout << u << " " << v << endl;
adj[u].push_back(v);
adj[v].push_back(u);
};
DSU D; D.init(N);
set<pi> R;
for(int t = 0; t < 2 * N; t++) {
int i = E[t].f;
// cout << t << " -> " << i << endl;
if (E[t].s == +1) {
vi conn;
for(auto r : R) {
if (r.f > B[i]) break;
conn.push_back(r.s);
// cout << i << " - " << r.s << endl;
}
for(auto x : conn) {
D.unite(x, i); ae(i, x);
if (D.siz(x) > 1) {
pi p = D.top2(x);
// cout << i << " " << p.s << " " << p.f << endl;
if (B[i] > p.f) ae(i, p.s);
}
}
D.ins(i, mp(B[i], i));
if (size(conn) == 0) R.insert(D.top(i));
}
if (E[t].s == -1) {
R.erase(D.top(i));
D.erase(i, mp(B[i], i));
if (D.siz(i) > 0) R.insert(D.top(i));
}
}
// cout << ans << nl;
vi C(N, -1); bool bi = 1;
function<void(int)> dfs = [&](int u) {
// cout << u << endl;
for(auto& v : adj[u]) {
if (C[v] == -1) C[v] = C[u] ^ 1, dfs(v);
else {
if (C[v] == C[u]) bi = 0;
}
}
};
int ans = 0;
for(int i = 0; i < N; i++) if (C[i] == -1) {
ans++; C[i] = 0; dfs(i);
// cout << endl;
}
if (!bi) {
cout << 0 << nl;
return 0;
}
const int MOD = 1e9 + 7;
ll ANS = 1, x = 2;
for(; ans; ans /= 2, x = (x * x) % MOD) if (ans & 1) ANS = (ANS * x) % MOD;
cout << ANS << nl;
return 0;
}
