#include<bits/stdc++.h>
using namespace std;
ofstream fout ("out.txt");
#define ll long long
#define int ll
#define F first
#define S second
#define MP make_pair
#define pb push_back
#define pii pair<int,int>
#define REP(i,a,b) for(int i=a; i<b; i++)
const int MX=2e6+3, mod=1e9+7;
int n, arr[MX], pp[MX], ans=1, ps[MX], fen[MX];
void ADD(int pl, int val){
for(; pl<MX; pl+=pl&-pl) fen[pl]+=val;
}
int ASK(int pl){
int sum=0;
for(; pl>0; pl-=pl&-pl) sum+=fen[pl];
return sum;
}
int pw(int a, int b){
if(!b) return 1;
int nsf=pw(a,b/2);
nsf=nsf*nsf%mod;
if(b&1) nsf*=a;
return nsf%mod;
}
int32_t main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//cout<<(1&-1)<<endl;
cin>>n;
REP(i,0,n){
int a, b;
cin>>a>>b;
arr[a]=b;
}
stack<int> a, b;
REP(i,1,2*n+1){
//cout<<i<<endl;
if(a.size() && i==a.top()) a.pop();
if(b.size() && i==b.top()) b.pop();
//cout<<i<<endl;
if(arr[i]){
ans=ans*2%mod;
int cnt=ASK(arr[i])-ASK(i);
ans=ans*pw(pw(2,cnt),mod-2)%mod;
ADD(arr[i],1);
//cout<<i<<endl;
//if(a.size()) cout<<" A "<<a.top()<<endl;
//if(b.size()) cout<<" B "<<b.top()<<endl;
if(!a.size()){
//cout<<i<<endl;
if(!b.size()) b.push(arr[i]);
else{
int cnt=b.top();
if(cnt>arr[i]) b.push(arr[i]);
else a.push(arr[i]);
}
}
else{
if(!b.size()){
if(a.top()>arr[i]) a.push(arr[i]);
else b.push(arr[i]);
continue;
}
int cnta=a.top(), cntb=b.top();
if(arr[i]<cnta && arr[i]<cntb){
if(cnta<cntb) a.push(arr[i]);
else b.push(arr[i]);
}
else if(arr[i]<cnta){
a.push(arr[i]);
}
else if(arr[i]<cntb){
b.push(arr[i]);
}
else{
//return cout<<0<<endl, 0;
}
}
}
}
cout<<ans<<endl;
return 0;
}
