#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
const int mod = 1e9 + 7, maxn = 1 << 20;
pair<int, int> st[2][maxn * 2]; // prvy je maximovy, druhy je minimovy
pair<int, int> nic[2] = { {-1, -1}, {maxn + 1, -1} };
void upd(int ly, int i, pair<int, int> p)
{
st[ly][i += maxn] = p;
for (i = (i >> 1); i > 0; i >>= 1)
{
if (ly == 0) st[ly][i] = max(st[ly][i << 1], st[ly][i << 1 | 1]);
if (ly == 1) st[ly][i] = min(st[ly][i << 1], st[ly][i << 1 | 1]);
}
}
pair<int, int> query(int ly, int l, int r)
{
pair<int, int> ans = nic[ly];
for (l += maxn, r += maxn + 1; l < r; l >>= 1, r >>= 1)
{
if (l & 1) ans = l ? min(ans, st[ly][l++]) : max(ans, st[ly][l++]);
if (r & 1) ans = l ? min(ans, st[ly][--r]) : max(ans, st[ly][--r]);
}
return ans;
}
vector<int> col(maxn, -1), l(maxn), r(maxn);
int n;
void dfs(int u, int c)
{
upd(0, l[u], nic[0]);
upd(1, r[u], nic[1]);
col[u] = c;
while (true)
{
int v = query(0, 0, l[u] - 1).second;
if (v == -1 || r[v] < l[u]) break;
dfs(v, (c ^ 1));
}
while (true)
{
int v = query(1, r[u] + 1, maxn).second;
if (v == -1 || l[v] > r[u]) break;
dfs(v, (c ^ 1));
}
}
bool check(int c)
{
vector<int> s, ch(2 * n + 1, -1);
for (int i = 0; i < n; i++) if (col[i] == c)
ch[l[i]] = i, ch[r[i]] = n + i;
for (int i = 0; i < 2 * n; i++)
{
if (0 <= ch[i] && ch[i] < n) s.push_back(ch[i]);
else if (ch[i] >= n)
{
if (s.back() != ch[i] - n) return false;
s.pop_back();
}
}
return true;
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
for (int i = 0; i < 2; i++) for (int j = 0; j < 2 * maxn; j++) st[i][j] = nic[i];
cin >> n;
for (int i = 0; i < n; i++)
{
cin >> l[i] >> r[i];
upd(0, l[i], { r[i],i });
upd(1, r[i], { l[i],i });
}
int ans = 1;
for (int i = 0; i < n; i++) if (col[i] == -1)
{
dfs(i, 0);
ans = (ans << 1) % mod;
}
if (check(0) && check(1)) cout << ans << "\n";
else cout << 0 << "\n";
return 0;
}
