#include <bits/stdc++.h>
using namespace std;
#define dbgv(v) cout<<#v<<" = "; f(i,0,v.size()) cout<<v[i]<<" "; cout<<endl
#define dbga(a,x,y) cout<<#a<<" = "; f(i,x,y) cout<<a[i]<<" "; cout<<endl
#define erorp(x) cout<<#x<<"={"<<(x.F)<<" , "<<x.S<<"}"<<endl
#define eror(x) cout<<#x<<'='<<(x)<<endl
#define f_(i,a,b) for(int i=a;i>=b;i--)
#define f(i,a,b) for(int i=a;i<b;i++)
#define nb(x) __builtin_popcount(x)
#define all(v) v.begin(),v.end()
#define bit(n,k) (((n)>>(k))&1)
#define Add(x,y) x=(x+y)%mod
#define maxm(a,b) a=max(a,b)
#define minm(a,b) a=min(a,b)
#define lst(x) x[x.size()-1]
#define sz(x) int(x.size())
#define mp make_pair
#define ll long long
#define pb push_back
#define S second
#define F first
const int N=4e6+99,mod=1e9+7;
int n,m,ans=1,s[N],t[N],vis[N],mark[N],dist[N],segmx[N<<2],segmn[N<<2],tad[N],ted[N];
// mn : s mx : t
void updmn(int id){
segmn[id]=min(segmn[id<<1],segmn[id<<1|1]);
}
void updmx(int id){
segmx[id]=max(segmx[id<<1],segmx[id<<1|1]);
}
void add(int x){
int id;
id=t[x]+m;
segmn[id]=s[x];
id/=2;
for(;id>0;id/=2){
updmn(id);
}
id=s[x]+m;
segmx[id]=t[x];
id/=2;
for(;id>0;id/=2){
updmx(id);
}
}
void del(int x){
int id;
id=t[x]+m;
segmn[id]=s[0];
id/=2;
for(;id>0;id/=2){
updmn(id);
}
id=s[x]+m;
segmx[id]=t[0];
id/=2;
for(;id>0;id/=2){
updmx(id);
}
}
int getmn(int l, int r){
int res=N+N;
for (l += m, r += m; l < r; l >>= 1, r >>= 1) {
if (l&1){
minm(res,segmn[l++]);
}
if (r&1){
minm(res,segmn[--r]);
}
}
return res;
}
int getmx(int l, int r){
int res=0;
for (l += m, r += m; l < r; l >>= 1, r >>= 1) {
if (l&1){
maxm(res,segmx[l++]);
}
if (r&1){
maxm(res,segmx[--r]);
}
}
return res;
}
void bfs(int x){
queue<int> q;
q.push(x);
vis[x]=1;
del(x);
while(q.size()){
int u=q.front();
//eror(u);
q.pop();
vis[u]=1;
while(getmn(s[u],t[u])<s[u]){
int v=mark[getmn(s[u],t[u])];
dist[v]=dist[u]^1;
q.push(v);
del(v);
//eror(v);
}
while(t[u]<getmx(s[u],t[u])){
int v=mark[getmx(s[u],t[u])];
dist[v]=dist[u]^1;
q.push(v);
del(v);
//eror(v);
}
}
ans=2ll*ans%mod;
}
void check(){
f(b,0,2){
fill(tad,tad+N,0);
fill(ted,ted+N,0);
f(i,1,n+1){
if(dist[i]==b){
tad[s[i]]=i;
ted[t[i]]=i;
}
}
vector<int> v;
f(i,1,2*n+1){
//dbgv(v);
if(tad[i]){
v.pb(tad[i]);
}
if(ted[i]){
if(ted[i]!=v.back()){
cout<<0;
exit(0);
}
v.pop_back();
}
}
}
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
fill(segmn,segmn+N,N);
s[0]=N;
cin>>n; m=2*n+10;
f(i,1,n+1){
cin>>s[i]>>t[i];
mark[s[i]]=i;
mark[t[i]]=i;
add(i);
}
f(i,1,n+1){
if(!vis[i]){
bfs(i);
}
}
check();
cout<<ans;
}
