#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ar array
#define vt vector
#define pq priority_queue
#define pu push
#define pub push_back
#define em emplace
#define emb emplace_back
#define mt make_tuple
#define all(x) x.begin(), x.end()
#define allr(x) x.rbegin(), x.rend()
#define allp(x, l, r) x.begin() + l, x.begin() + r
#define len(x) (int)x.size()
#define uniq(x) unique(all(x)), x.end()
using ll = long long;
using ld = long double;
using ull = unsigned long long;
template<class Fun> class y_combinator_result {
Fun fun_;
public:
template<class T> explicit y_combinator_result(T &&fun): fun_(std::forward<T>(fun)) {}
template<class ...Args> decltype(auto) operator()(Args &&...args) { return fun_(std::ref(*this), std::forward<Args>(args)...); }
};
template<class Fun> decltype(auto) y_combinator(Fun &&fun) { return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun)); }
template <class T, size_t N>
void re(array <T, N>& x);
template <class T>
void re(vt <T>& x);
template <class T>
void re(T& x) {
cin >> x;
}
template <class T, class... M>
void re(T& x, M&... args) {
re(x), re(args...);
}
template <class T>
void re(vt <T>& x) {
for(auto& it : x) re(it);
}
template <class T, size_t N>
void re(array <T, N>& x) {
for(auto& it : x) re(it);
}
template <class T, size_t N>
void wr(const array <T, N>& x);
template <class T>
void wr(const vt <T>& x);
template <class T>
void wr(const T& x) {
cout << x;
}
template <class T, class ...M>
void wr(const T& x, const M&... args) {
wr(x), wr(args...);
}
template <class T>
void wr(const vt <T>& x) {
for(auto it : x) wr(it, ' ');
}
template <class T, size_t N>
void wr(const array <T, N>& x) {
for(auto it : x) wr(it, ' ');
}
template<class T, class... M>
auto mvt(size_t n, M&&... args) {
if constexpr(sizeof...(args) == 1)
return vector<T>(n, args...);
else
return vector(n, mvt<T>(args...));
}
void set_fixed(int p = 0) {
cout << fixed << setprecision(p);
}
void set_scientific() {
cout << scientific;
}
void Open(const string& name) {
// #ifndef ONLINE_JUDGE
(void)!freopen((name + ".in").c_str(), "r", stdin);
(void)!freopen((name + ".out").c_str(), "w", stdout);
// #endif
}
const int N = 2e5 + 5;
vt <int> t[N << 2];
int idx[N << 2], par[N], d[N], a[N], b[N], mn[N], m[N << 1], vis[N];
inline int find(int u) {
if (par[u] == u)
return u;
int p = find(par[u]);
d[u] ^= d[par[u]];
return par[u] = p;
}
inline bool unite(int u, int v, int w) {
int ru = find(u), rv = find(v);
if (ru == rv) {
return (d[u] ^ d[v]) == w;
} else {
d[ru] = w ^ d[u] ^ d[v];
par[ru] = rv;
return true;
}
assert(false);
return false;
}
void build(int v, int tl, int tr) {
idx[v] = 1;
if (tl == tr) {
if (m[tl]) {
t[v].pub(m[tl]);
}
return;
}
int tm = (tl + tr) / 2;
build(v * 2, tl, tm);
build(v * 2 + 1, tm + 1, tr);
merge(all(t[v * 2]), all(t[v * 2 + 1]), back_inserter(t[v]),
[&](const int& i, const int& j) {
return a[i] < a[j];
});
}
bool query(int i, int v, int tl, int tr, int l, int r) {
if (l <= tl && tr <= r) {
if (len(t[v]) == 0 || a[t[v][0]] > a[i])
return true;
bool ret = 1;
ret &= unite(i, t[v][0], 1);
while (idx[v] < len(t[v]) && a[t[v][idx[v]]] < a[i]) {
ret &= unite(t[v][idx[v]], t[v][0], 0);
idx[v]++;
}
return ret;
} else {
int tm = (tl + tr) / 2;
if (r <= tm) return query(i, v * 2, tl, tm, l, r);
else if (l > tm) return query(i, v * 2 + 1, tm + 1, tr, l, r);
else return query(i, v * 2, tl, tm, l, r) & query(i, v * 2 + 1, tm + 1, tr, l, r);
}
assert(false);
return false;
}
void solve() {
int n; re(n);
for (int i = 1; i <= n; ++i) {
re(a[i], b[i]);
par[i] = m[b[i]] = i;
}
build(1, 1, 2 * n);
bool can = 1;
for (int i = 1; i <= n; ++i)
can &= query(i, 1, 1, 2 * n, a[i], b[i] - 1);
if (!can) {
return wr("0\n");
}
const int mod = 1e9 + 7;
ll res = 1;
vt <bool> vis(n + 1);
for (int i = 1; i <= n; ++i) {
if(vis[find(i)]) {
continue;
}
vis[find(i)] = 1;
res = (res * 2) % mod;
}
wr(res);
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//Open("a");
int t = 1;
for(;t;t--) {
solve();
}
return 0;
}
