#include<bits/stdc++.h>
using namespace std;
#define int long long
//shouldn't need, just in case...
int eve[2000005];
list<list<int> > luol;
list<int> tmp;
bool mk[1000005];
int par[1000005],sz[1000005];
int getr(int x){
if(par[x]==-1)return x;
int t=getr(par[x]);
if(mk[par[x]])mk[x]=!mk[x];
return par[x]=t;
}
bool bruh=false;
int c,d;
void merge(int a,int b){
//cout<<"MERGE"<<a<<' '<<b<<'\n';
c=getr(a);d=getr(b);
if(c==d){
//cout<<"path1\n";
//cout<<a<<' '<<b<<' '<<mk[a]<<mk[b]<<'\n';
if(mk[a]==mk[b])bruh=true;
return;
}
if(sz[c]<sz[d]){swap(c,d);swap(a,b);}
par[d]=c;
if(mk[a]==mk[b])mk[d]=true;//roots don't have marks so...
sz[c]+=sz[d];
}
int32_t main(){
ios_base::sync_with_stdio(false);cin.tie(0);
int n;
cin>>n;
int a,b;
for(int i=1;i<=n;i++){
cin>>a>>b;
eve[a]=i;
eve[b]=-i;
sz[i]=1;par[i]=-1;
}
vector<int> st;
for(int i=1;i<=n+n;i++){
if(eve[i]>0)st.push_back(eve[i]);
else{
for(int j=st.size()-1;j>=0;j--){
if(st[j]==-eve[i]){
st.erase(st.begin()+j);
break;
}
merge(st[j],-eve[i]);
}
}
//for(int x:st)cout<<x<<' ';cout<<'\n';
}
if(bruh)cout<<0;
else{
int ans=1;
for(int i=1;i<=n;i++){
if(par[i]==-1){
ans<<=1;
ans%=1000000007;
}
}
cout<<ans;
}
return 0;
}
