//Challenge: Accepted
#include <iostream>
#include <algorithm>
#include <utility>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#define ll long long
#define maxn 2000005
#define mod 1000000007
#define pii pair<int, int>
#define ff first
#define ss second
using namespace std;
struct obj{
int l, r, id;
obj() {
l = 0, r = 0, id = 0;
}
obj(int a, int b, int c) {
l = a, r = b, id = c;
}
};
obj a[maxn];
int mi[4 * maxn], ma[4 * maxn];
void modify(int cur, int l, int r, int ind, int val, int type) {
if (r <= l) return;
if (r - l == 1) {
if (type == 0) mi[cur] = val;
else ma[cur] = val;
return;
}
int mid = (l + r) / 2;
if (ind < mid) modify(cur * 2, l, mid, ind, val, type);
else modify(cur * 2 + 1, mid, r, ind, val, type);
if (type == 0) mi[cur] = min(mi[cur * 2], mi[cur * 2 + 1]);
else ma[cur] = max(ma[cur * 2], ma[cur * 2 + 1]);
}
int query(int cur, int l, int r, int ql, int qr, int type) {
if (r <= l || ql >= r || qr <= l) return type ? -1 : 1<<30;
if (ql <= l && qr >= r) return type ? ma[cur] : mi[cur];
int mid = (l + r) / 2;
if (type) return max(query(cur * 2, l, mid, ql, qr, type), query(cur * 2 + 1, mid, r, ql, qr, type));
else return min(query(cur * 2, l, mid, ql, qr, type), query(cur * 2 + 1, mid, r, ql, qr, type));
}
int other[maxn], id[maxn], col[maxn];
bool islef[maxn], vis[maxn];
vector<vector<int> > com;
int n;
inline void del(int val, int type) {
//cout << a[id[val]].l << " " << a[id[val]].r << endl;
//cout << other[val] << " " << (type ? -1 : 1<<30) << endl;
if (vis[id[val]]) return;
vis[id[val]] = 1;
modify(1, 0, 2 * n, other[val], type ? -1 : 1<<30, type);
modify(1, 0, 2 * n, val, type ? 1<<30 : -1, type ^ 1);
}
inline bool cmp(int x, int y) {
return a[x].l < a[y].l;
}
bool poss(vector<int> &x) {
stack<int> stk;
sort(x.begin(), x.end(), cmp);
bool ret = true;
for (int c = 0;c < 2;c++) {
for (int i = 0;i < x.size();i++) {
if (col[x[i]] != c) continue;
while (stk.size() && a[x[i]].l > stk.top()) stk.pop();
if (stk.size() && a[x[i]].r > stk.top()) return false;
else stk.push(a[x[i]].r);
}
while (stk.size()) stk.pop();
}
return ret;
}
int main() {
ios_base::sync_with_stdio(0);cin.tie(0);
cin >> n;
for (int i = 0;i < 4 * maxn;i++) mi[i] = 1<<30, ma[i] = -1; //0 based values
for (int i = 0;i < n;i++) {
cin >> a[i].l >> a[i].r, a[i].id = i;
a[i].l--, a[i].r--;
islef[a[i].l] = 1;
other[a[i].l] = a[i].r, other[a[i].r] = a[i].l;
id[a[i].l] = id[a[i].r] = i;
modify(1, 0, 2 * n, a[i].l, a[i].r, 1);
modify(1, 0, 2 * n, a[i].r, a[i].l, 0);
}
for (int st = 0;st < n;st++) {
if (vis[st]) continue;
queue<pii> que;
que.push(make_pair(st, 1));
vector<int> add;
while (que.size()) {
int cur = que.front().ff;
col[cur] = que.front().ss;
que.pop();
add.push_back(cur);
//cout << cur << endl;
del(a[cur].r, 1);
int val = query(1, 0, 2 * n, a[cur].l, a[cur].r + 1, 1); //max part
while (val > a[cur].r) {
//cout << val << endl;
del(val, 1);
que.push(make_pair(id[val], col[cur] ^ 1));
val = query(1, 0, 2 * n, a[cur].l, a[cur].r + 1, 1);
}
val = query(1, 0, 2 * n, a[cur].l, a[cur].r + 1, 0);
while (val < a[cur].l) {
//cout << a[id[val]].l << " " << a[id[val]].r << endl;
del(val, 0);
que.push(make_pair(id[val], col[cur] ^ 1));
val = query(1, 0, 2 * n, a[cur].l, a[cur].r + 1, 0);
}
}
//cout << endl;
com.push_back(add);
}
ll ans = 1;
for (int i = 0;i < com.size();i++) {
ans = (ans * (poss(com[i]) ? 2 : 0)) % mod;
if (ans == 0) break;
}
cout << ans << "\n";
}
/*
4
1 3
2 5
4 8
6 7
3
1 4
2 5
3 6
5
1 4
2 10
6 9
7 8
3 5
8
1 15
2 5
3 8
4 6
14 16
7 9
10 13
11 12
5
2 5
4 7
6 8
1 9
3 10
*/
