/**
* author : pham van sam
* created : 29.08.2023 21:47:12
**/
#include <bits/stdc++.h>
using namespace std;
#define MASK(x) (1LL << (x))
#define BIT(x, i) (((x) >> (i)) & 1)
#define ALL(x) (x).begin(), (x).end()
#define REP(i, n) for (int i = 0, _n = n; i < _n; ++i)
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
#define FORE(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define debug(...) "[" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#ifdef LOCAL
#include "debug.h"
#else
#define clog if(false) cerr
#endif
template <class A, class B> bool minimize(A &a, B b) { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b) { if (a < b) { a = b; return true; } return false; }
const int Mod = 1e9 + 7;
void add(int &x, int y) {
if((x += y) >= Mod) x -= Mod;
if(x < 0) x += Mod;
}
template < class T, T (*f) (T, T), T (*e) ()>
struct segment_tree {
vector <T> tree;
int n;
void update(int u, int p) {
u--;
for(tree[u += n] += p; u >>= 1; ) {
tree[u] = f(tree[u << 1], tree[u << 1 | 1]);
}
}
void set(int u, int p) {
u--;
for (tree[u += n] = p; u >>= 1; ) {
tree[u] = f(tree[u << 1], tree[u << 1 | 1]);
}
}
T get(int p) {
return tree[p += n - 1];
}
T get(int l, int r) {
l--;
T resl = e(), resr = e();
for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
if(l & 1) resl = f(resl, tree[l++]);
if(r & 1) resr = f(tree[--r], resr);
}
return f(resl, resr);
}
segment_tree(int n = 0) : n(n), tree(n << 2 | 1) {
fill(tree.begin(), tree.end(), e());
}
};
namespace _max_ {
int op(int a, int b) { return a > b ? a : b; }
int e() { return numeric_limits<int>::min(); }
};
namespace _min_ {
int op(int a, int b) { return a < b ? a : b; }
int e() { return numeric_limits<int>::max(); }
};
const int MAXN = 1e6 + 5;
template <class T> using It_Max = segment_tree <T, _max_::op, _max_::e>;
template <class T> using It_Min = segment_tree <T, _min_::op, _min_::e>;
int N, dd[MAXN], pos[2 * MAXN];
struct Segment {
int l, r;
Segment(int _l = 0, int _r = 0) : l(_l), r(_r) {}
bool operator < (const Segment &other) const { return l < other.l || (l == other.l and r < other.r); }
} A[MAXN];
void you_make_it(void) {
cin >> N;
FOR(i, 1, N) cin >> A[i].l >> A[i].r;
sort(A + 1, A + N + 1);
It_Max <int> itMax(2 * N);
It_Min <int> itMin(2 * N);
FOR(i, 1, N) {
itMin.set(A[i].r, A[i].l);
itMax.set(A[i].l, A[i].r);
pos[A[i].l] = pos[A[i].r] = i;
}
memset(dd, -1, sizeof dd);
function <void(int, int)> dfs = [&](int u, int color) {
if(dd[u] != -1 and dd[u] != color) {
cout << 0;
exit(0);
}
clog << u << " ";
dd[u] = color;
itMax.set(A[u].l, _max_::e());
itMin.set(A[u].r, _min_::e());
while(itMax.get(A[u].l, A[u].r) > A[u].r) {
int i = pos[itMax.get(A[u].l, A[u].r)];
dfs(i, color ^ 1);
}
while(itMin.get(A[u].l, A[u].r) < A[u].l) {
int i = pos[itMin.get(A[u].l, A[u].r)];
dfs(i, color ^ 1);
}
};
int ans = 1;
FOR(i, 1, N) if(dd[i] == -1) {
dfs(i, 0);
add(ans, ans);
clog << endl;
}
stack <int> check[2];
FOR(i, 1, 2 * N) {
int u = pos[i];
if(i == A[u].l) check[dd[u]].push(u);
else {
if(check[dd[u]].top() != u) {
cout << 0;
return;
}
check[dd[u]].pop();
}
}
cout << ans;
}
signed main() {
#ifdef LOCAL
freopen("TASK.inp", "r", stdin);
freopen("TASK.out", "w", stdout);
#endif
file("port_facility");
auto start_time = chrono::steady_clock::now();
cin.tie(0), cout.tie(0) -> sync_with_stdio(0);
you_make_it();
auto end_time = chrono::steady_clock::now();
cerr << "\nExecution time : " << chrono::duration_cast <chrono::milliseconds> (end_time - start_time).count() << "[ms]" << endl;
return (0 ^ 0);
}
// Dream it. Wish it. Do it.
