#pragma GCC optimize("O3")
#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cassert>
#include <stack>
#include <queue>
using namespace std;
using ll = long long;
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#define MAX(a, b) (((a) < (b)) ? (b) : (a))
int const nmax = 2000000;
int const modulo = 1000000007;
struct Port{
int x;
int y;
bool operator < (Port const &a) const {
return y < a.y;
}
} v[1 + nmax];
int seen[1 + nmax];
vector<int> g[1 + nmax];
void addedge(int x, int y){
g[x].push_back(y);
g[y].push_back(x);
}
namespace SegmentTree{
vector<int> aint[1 + nmax * 5];
void update(int node, int from, int to, int x, int y, int id){
if(from == x && to == y)
aint[node].push_back(id);
else {
int mid = (from + to)/ 2;
if(x <= mid)
update(node * 2, from, mid, x, MIN(y, mid), id);
if(mid + 1 <= y)
update(node * 2 + 1, mid + 1, to, MAX(mid + 1, x), y, id);
}
}
void query(int node, int from, int to, int x, int id){
for(int i = 0; i < aint[node].size(); i++){
int val = aint[node][i];
addedge(val, id);
}
while(1 < aint[node].size())
aint[node].pop_back();
if(from < to){
int mid = (from + to) / 2;
if(x <= mid)
query(node * 2, from, mid, x, id);
else
query(node * 2 + 1, mid + 1, to, x, id);
}
}
}
void dfs(int node, int color){
queue<int> q;
q.push(node);
seen[node] = color;
while(0 < q.size()){
int node = q.front();
q.pop();
for(int h = 0; h < g[node].size(); h++){
int to = g[node][h];
if(seen[to] == 0) {
q.push(to);
seen[to] = 3 - seen[node];
}
}
}
}
stack<int> st[3];
int event[1 + 2 * nmax];
bool valid(int n){
for(int i = 1;i <= n; i++) {
event[v[i].x] = i;
event[v[i].y] = -i;
}
for(int i = 1;i <= 2 * n; i++){
if(0 < event[i])
st[seen[event[i]]].push(event[i]);
else {
int id = -event[i];
if(0 == st[seen[id]].size() || st[seen[id]].top() != id)
return 0;
st[seen[id]].pop();
}
}
return 1;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
for(int i = 1; i <= n; i++)
cin >> v[i].x >> v[i].y;
sort(v + 1, v + n + 1);
int lim = 2 * n;
for(int i = 1; i <= n; i++){
SegmentTree::query(1, 1, lim, v[i].x, i);
if(v[i].x + 1 <= v[i].y - 1)
SegmentTree::update(1, 1, lim, v[i].x + 1, v[i].y - 1, i);
}
int result = 1;
for(int i = 1;i <= n; i++)
if(seen[i] == 0) {
dfs(i, 1);
result = 1LL * result * 2 % modulo;
}
if(valid(n) == 1)
cout << result;
else
cout << 0;
return 0;
}
