#include <iostream>
#include <cstdio>
#include <algorithm>
#include <array>
#include <stack>
#include <deque>
using namespace std;
#define endl '\n'
#define ll long long
#define pi pair<int, int>
#define f first
#define s second
typedef pair<deque<int>, deque<int>> T;
const int mod = 1000000007;
const int mxn = 1000001;
int n;
pi a[mxn];
stack<T> stk;
int f(int x){
if(!x) return stk.top().f.empty() ? 2 * n + 2 : stk.top().f.front();
else return stk.top().s.empty() ? 2 * n + 2 : stk.top().s.front();
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n;
for(int i = 0; i < n; i++) cin >> a[i].f >> a[i].s;
a[n] = {2 * n + 1, 2 * n + 1};
sort(a, a + n);
int ret = 1;
for(int i = 0; i <= n; i++){
while(!stk.empty()){
for(int j = 0; j < 2; j++){
while(f(j) < a[i].f){
if(!j) stk.top().f.pop_front();
else stk.top().s.pop_front();
}
}
if(f(0) > f(1)) swap(stk.top().f, stk.top().s);
if(!stk.top().f.empty()) break;
stk.pop(), (ret *= 2) %= mod;
}
if(stk.empty() || a[i].s < f(0)){
stk.push(T());
stk.top().f.push_front(a[i].s);
}else{
while(stk.size() > 1 && stk.top().s.empty()){
T x;
swap(stk.top(), x);
stk.pop();
if(a[i].s < f(0)){
stk.push(T());
swap(stk.top(), x);
break;
}
if(x.f.size() < stk.top().f.size()){
while(!x.f.empty()){
stk.top().f.push_front(x.f.back());
x.f.pop_back();
}
}else{
swap(x.f, stk.top().f);
while(!x.f.empty()){
stk.top().f.push_back(x.f.front());
x.f.pop_front();
}
}
}
if(a[i].s > f(1)){
ret = 0;
break;
}
stk.top().s.push_front(a[i].s);
}
}
cout << ret << endl;
return 0;
}
