#include<bits/stdc++.h>
#define taskname "B"
using namespace std;
const int mod = 1e9 + 7;
int n;
namespace sub1{
void solve(){
vector<int>a(n), b(n), p(n << 1 | 1);
for(int i = 0; i < n; i++){
cin >> a[i] >> b[i];
p[b[i]] = -(p[a[i]] = i + 1);
}
int ans = 1 << n;
for(int mask = (1 << n) - 1; mask > -1; mask--){
vector<stack<int>>st(2);
for(int i = 1; i <= (n << 1); i++){
bool bit = bool(mask >> (abs(p[i]) - 1) & 1);
if(p[i] > 0){
st[bit].push(p[i]);
}
else{
if(st[bit].top() != -p[i]){
ans--;
break;
}
st[bit].pop();
}
}
}
cout << ans;
}
}
namespace sub2{
void solve(){
vector<int>a(n), b(n);
vector<vector<int>>g(n);
auto inside = [&] (int i, int l, int r){
return l < i && r > i;
};
for(int i = 0; i < n; i++){
cin >> a[i] >> b[i];
for(int j = 0; j < i; j++){
if((inside(a[j], a[i], b[i]) && inside(b[i], a[j], b[j])) || (inside(a[i], a[j], b[j]) && inside(b[j], a[i], b[i]))){
g[i].emplace_back(j);
g[j].emplace_back(i);
}
}
}
vector<int>color(n, -1);
int ans = 1;
auto dfs = [&] (auto&& self, int s) -> void{
for(int& d : g[s]){
if(color[d] == -1){
color[d] = color[s] ^ 1;
self(self, d);
}
else if(color[s] == color[d]){
cout << 0;
exit(0);
}
}
};
for(int i = 0; i < n; i++){
if(color[i] == -1){
color[i] = 0;
dfs(dfs, i);
ans = (ans << 1) % mod;
}
}
cout << ans;
}
}
namespace sub34{
const int lim = 1e6 + 5;
vector<int>g[lim];
pair<int, int>st[lim << 3];
pair<int, int>p[lim << 1];
int L[lim << 1];
void build(int id, int l, int r){
if(l == r){
st[id] = p[l];
return;
}
int m = (l + r) >> 1;
build(id << 1, l, m);
build(id << 1 | 1, m + 1, r);
st[id] = max(st[id << 1], st[id << 1 | 1]);
}
pair<int, int>get(int id, int l, int r, int u, int v){
if(l > v || r < u){
return make_pair(-1, -1);
}
if(u <= l && v >= r){
return st[id];
}
int m = (l + r) >> 1;
return max(get(id << 1, l, m, u, v), get(id << 1 | 1, m + 1, r, u, v));
}
void add_edge(int u, int v){
g[u].emplace_back(v);
g[v].emplace_back(u);
}
pair<int, int>find_next(int l, int r){
int low = l + 1, high = r, p = -1, ans_r = -1;
pair<int, int>temp, ans = make_pair(-1, -1);
while(low <= high){
int mid = (low + high) >> 1;
if((temp = get(1, 1, n << 1, l + 1, mid)).first > r){
ans = temp;
high = (p = mid) - 1;
}
else{
low = mid + 1;
}
}
return ans;
}
void solve(){
fill(p, p + (n << 1 | 1), make_pair(-1, -1));
fill(st, st + (n << 3), make_pair(-1, -1));
for(int i = 0; i < n; i++){
int l, r;
cin >> l >> r;
p[L[i] = l] = make_pair(r, i);
}
build(1, 1, n << 1);
for(int i = 1; i <= (n << 1); i++){
if(p[i].first != -1){
auto& [r, I] = p[i];
pair<int, int>j = find_next(i, r);
if(j.first != -1){
add_edge(j.second, I);
while(true){
int temp = j.first;
j = find_next(L[j.second], r);
if(j.first == -1){
break;
}
if(j.first > temp){
return void(cout << 0);
}
add_edge(j.second, I);
}
}
}
}
vector<int>color(n, -1);
int ans = 1;
auto dfs = [&] (auto&& self, int s) -> void{
for(int& d : g[s]){
if(color[d] == -1){
color[d] = color[s] ^ 1;
self(self, d);
}
}
};
for(int i = 0; i < n; i++){
if(color[i] == -1){
color[i] = 0;
dfs(dfs, i);
ans = (ans << 1) % mod;
}
}
cout << ans;
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if(fopen(taskname".inp", "r")){
freopen(taskname".inp", "r", stdin);
}
cin >> n;
if(n <= 20){
sub34::solve();
}
else if(n <= 2000){
sub34::solve();
}
else{
sub34::solve();
}
}
