#include <bits/stdc++.h>
#define pw2(i) (1LL << (i))
#define all(v) (v).begin(), (v).end()
using namespace std;
using ll = long long;
/*------------- I alone decide my fate ! -------------*/
const ll MOD = 1e9 + 7;
int N, color[1000009];
pair <int, int> a[1000009];
struct SegmentTree {
vector<pair<int,int>> it;
SegmentTree(){}
void init(int size) {
it.assign(4 * size + 5, {-1000000000, 0});
}
void update(int id, int l, int r, int pos, pair<int,int> val) {
if (l > pos || r < pos) return;
if (l == r) {
it[id] = val;
return;
}
int mid = (l + r) >> 1;
update(id*2, l, mid, pos, val);
update(id*2 + 1, mid + 1, r, pos, val);
it[id] = max(it[id*2], it[id*2 + 1]);
}
pair<int,int> getPos(int id, int l, int r, int u, int v) {
if (u > v) return {-1000000000, 0};
if (l > v || r < u) return {-1000000000, 0};
if (l >= u && r <= v) {
return it[id];
}
int mid = (l + r) >> 1;
return max(getPos(id*2, l, mid, u, v), getPos(id*2 + 1, mid + 1, r, u , v));
}
};
SegmentTree segTreeMax, segTreeMin;
void DFS(int u, int col) {
color[u] = col;
segTreeMax.update(1, 1, 2*N, a[u].first, {-1000000000, 0});
segTreeMin.update(1, 1, 2*N, a[u].second, {-1000000000, 0});
while (true) {
int v = segTreeMax.getPos(1, 1, 2 * N, a[u].first + 1, a[u].second - 1).second;
if (!v || a[v].second <= a[u].second) break;
DFS(v, col ^ 1);
}
while (true) {
int v = segTreeMin.getPos(1, 1, 2 * N, a[u].first + 1, a[u].second - 1).second;
if (!v || a[v].first >= a[u].first) break;
DFS(v, col ^ 1);
}
}
int st[1000009], event[2000009];
bool check(int tp) {
for (int i = 1; i <= 2 * N; ++i) event[i] = 0;
for (int i = 1; i <= N; i ++) {
if (color[i] == tp) {
event[a[i].first] = i;
event[a[i].second] = i;
}
}
int top = 0;
for (int i = 1; i <= 2 * N; i ++) {
if (event[i]) {
if (top > 0 && st[top] == event[i]) top --;
else st[++top] = event[i];
}
}
return (top == 0);
}
void solve() {
cin >> N;
for (int i = 1; i <= N; i ++) {
cin >> a[i].first >> a[i].second;
}
segTreeMax.init(2 * N);
segTreeMin.init(2 * N);
for (int i = 1; i <= N; i ++) {
segTreeMax.update(1, 1, 2*N, a[i].first, {a[i].second, i});
segTreeMin.update(1, 1, 2*N, a[i].second, {-a[i].first, i});
}
for (int i = 1; i <= N; i ++) color[i] = -1;
ll res = 1;
for (int i = 1; i <= N; i ++) {
if (color[i] == -1) {
DFS(i, 0);
res = (res * 2) % MOD;
}
}
if(!check(1) || !check(0)) cout << 0;
else cout << res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
solve();
return 0;
}
/*
How can you see into my eyes, like open doors?
Leading you down into my core, where I've become so numb
Without a soul, my spirit's sleeping somewhere cold
Until you find it here and bring it back home!
Wake me up! Wake me up inside
Can't wake up? Wake me up inside
*/
