#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int n, a[1001001], b[1001001], p[1001001], c[2002002], d[1001001];
priority_queue<array<int, 2>, vector<array<int, 2>>, greater<>> pq, s[1001001][2];
int find(int x) { return x == p[x] ? x : p[x] = find(p[x]); }
int merge(int x, int y) {
int k = d[x] == d[y];
if((x = find(x)) == (y = find(y))) return 0;
if(s[x][0].size()+s[x][1].size() > s[y][0].size()+s[y][1].size()) swap(x, y);
for(int i=0;i<2;i++) {
while(!s[x][i].empty()) {
auto [c, u] = s[x][i].top(); s[x][i].pop();
s[y][i^k].push({c, u}), d[u] = i^k;
}
}
p[x] = y;
return 1;
}
void add(int u, int i) {
for(int j=0;j<2;j++) {
while(!s[u][j].empty() && s[u][j].top()[0] <= i) s[u][j].pop();
if(!s[u][j].empty()) pq.push(s[u][j].top());
}
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for(int i=1;i<=n;i++) cin >> a[i] >> b[i];
for(int i=1;i<=n;i++) c[a[i]] = c[b[i]] = p[i] = i, s[i][0].push({b[i], i});
for(int i=1;i<=n+n;i++) {
int u = c[i];
if(i == b[u]) {
add(find(u), i);
continue;
}
int P = i;
while(!pq.empty() && pq.top()[0] < b[u]) {
auto [c, x] = pq.top(); pq.pop();
if(c <= P) continue;
P = c;
if(!merge(x, u) && d[x] == d[u]) return cout << 0, 0;
}
add(find(u), i);
}
int ans = 1;
for(int i=1;i<=n;i++) if(i == find(i)) ans = ans * 2 % 1000000007;
cout << ans;
}
