#include "bits/stdc++.h"
using namespace std;
template<typename A, typename B> ostream& operator<< (ostream& os, pair<A, B> x) {return os << "(" << x.first << ", " << ")";}
template<typename A> ostream& operator<< (ostream& os, vector<A> x) {string sep; os << "{"; for (A y : x) os << sep << "y", sep = ", "; return os << "}";}
#define ll long long
#define ld long double
#define all(a) (a).begin(), (a).end()
#define sui cin.tie(NULL), cout.tie(NULL), ios_base::sync_with_stdio(false);
#define lid id << 1
#define rid id << 1 | 1
#define mid ((r + l) >> 1)
const int MAX_N = 2e6 + 5;
const int MOD = 1e9 + 7;
const int INF = 1e9;
const int LOG = 30;
ll inv[MAX_N << 1];
ll fact[MAX_N << 1];
ll fact_inv[MAX_N << 1];
inline int md(ll x) {x %= MOD; return x + (x < 0 ? MOD : 0);}
inline int ADD(ll x, ll y) {return md(x+y);}
inline int SUB(ll x, ll y) {return md(x-y);}
inline int MUL(ll x, ll y) {return md(1ll*x*y);}
inline int POW(ll a, ll b) {int res = 1; while(b){if(b&1)res=MUL(res,a);a=MUL(a,a),b>>=1;}; return res;}
inline int DIV(ll a, ll b) {return MUL(a, POW(b, MOD - 2));}
inline int comb(int n, int k)
{
if (n < 0 || k < 0 || k < n) return 0;
return fact[n] * fact_inv[k] % MOD * fact_inv[n - k] % MOD;
}
inline void init()
{
inv[1] = 1;
for (int i = 2; i < (MAX_N << 1); i++) inv[i] = MOD - (MOD / i) * inv[MOD % i] % MOD;
fact[0] = 1;
fact_inv[0] = 1;
for (int i = 2; i < (MAX_N << 1); i++) fact[i] = fact[i - 1] * i % MOD, fact_inv[i] = fact_inv[i - 1] * inv[i] % MOD;
}
vector<int> adj[MAX_N];
pair<int, int> a[MAX_N];
int l1[MAX_N];
int r1[MAX_N];
int c[MAX_N];
bool mark[MAX_N];
int n;
pair<pair<int, int>, pair<int, int>> seg[MAX_N << 2];
void build(int l, int r, int id)
{
if (l == r - 1)
{
seg[id] = make_pair(a[l], a[l]);
return;
}
build(l, mid, lid);
build(mid, r, rid);
seg[id].first = min(seg[lid].first, seg[rid].first);
seg[id].second = max(seg[lid].second, seg[rid].second);
}
void upd(int x, int l, int r, int id)
{
if (l == r - 1)
{
seg[id] = make_pair(make_pair(INF, -1), make_pair(-INF, -1));
return;
}
if (x < mid) upd(x, l, mid, lid);
else upd(x, mid, r, rid);
seg[id].first = min(seg[lid].first, seg[rid].first);
seg[id].second = max(seg[lid].second, seg[rid].second);
}
pair<pair<int, int>, pair<int, int>> get(int s, int t, int l, int r, int id)
{
if (s <= l && t >= r) return seg[id];
if (s >= r || t <= l) return make_pair(make_pair(INF, -1), make_pair(-INF, -1));
auto x = get(s, t, l, mid, lid);
auto y = get(s, t, mid, r, rid);
return make_pair(min(x.first, y.first), max(x.second, y.second));
}
void dfs(int u, int c1)
{
mark[u] = true;
upd(l1[u], 0, n << 1, 1);
upd(r1[u], 0, n << 1, 1);
c[u] = c1;
while (true)
{
auto x = get(l1[u], r1[u] + 1, 0, n << 1, 1);
if (x.first.first < l1[u])
{
adj[u].push_back(x.first.second);
adj[x.first.second].push_back(u);
dfs(x.first.second, 1 - c1);
} else if (x.second.first > r1[u])
{
adj[u].push_back(x.second.second);
adj[x.second.second].push_back(u);
dfs(x.second.second, 1 - c1);
} else break;
}
}
pair<int, int> fen[MAX_N];
void add(int x, int y)
{
x++;
for (int i = x; i < MAX_N; i += i & (-i)) fen[i].first += y, fen[i].second++;
}
pair<int, int> get(int x)
{
x++;
pair<int, int> ans;
for (int i = x; i > 0; i -= i & (-i)) ans.first += fen[i].first, ans.second += fen[i].second;
return ans;
}
pair<int, int> get(int l, int r)
{
pair<int, int> ans1 = get(r);
pair<int, int> ans2 = get(l - 1);
return make_pair(ans1.first - ans2.first, ans1.second - ans2.second);
}
void solve()
{
cin >> n;
for (int i = 0; i < n; i++)
{
cin >> l1[i] >> r1[i];
l1[i]--;
r1[i]--;
a[l1[i]] = {r1[i], i};
a[r1[i]] = {l1[i], i};
}
build(0, n << 1, 1);
int ans = 1;
for (int i = 0; i < n; i++) if (!mark[i]) dfs(i, 0), ans = MUL(ans, 2);
for (int i = n * 2 - 1; i >= 0; i--)
{
if (a[i].first > i) continue;
auto x = get(a[i].first, i);
if ((x.first > 0 && x.first < x.second) || (x.second && min(x.first, 1) == c[a[i].second])) ans = 0;
add(a[i].first, c[a[i].second]);
}
cout << ans << "\n";
}
int main()
{
int tc = 1;
// cin >> tc;
while (tc--) solve();
}
