#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define ff first
#define ss second
//#define int long long
int l,r,n,t,m,mid,ans,sum,sum1,sum2,sum0,k,mod=1e9+7,c[2000005],a[1000005],b[1000005],vis[1000005];
int d_l[8000005],d_r[8000005];
vector <int> v,v1;
map <int,int> mp;
string s,s1;
bool b1;
int mx(int x,int y){
if(b[x]>=b[y]){
return x;
}
return y;
}
int mi(int x,int y){
if(a[x]<=a[y]){
return x;
}
return y;
}
int query_r(int v,int tl,int tr,int l,int r){
if(l>r){
return 0;
}
// cout<<v<<" "<<tl<<" "<<tr<<" "<<l<<" "<<r<<endl;
if(tl==l and tr==r){
return d_r[v];
}else{
int tm=(tl+tr)/2;
return mx(query_r(2*v,tl,tm,l,min(r,tm)),query_r(2*v+1,tm+1,tr,max(l,tm+1),r));
}
}
int query_l(int v,int tl,int tr,int l,int r){
if(l>r){
return n+1;
}
if(tl==l and tr==r){
return d_l[v];
}else{
int tm=(tl+tr)/2;
return mi(query_l(2*v,tl,tm,l,min(r,tm)),query_l(2*v+1,tm+1,tr,max(l,tm+1),r));
}
}
void update_l(int v,int tl,int tr,int pos,int val){
if(tl==pos and tr==pos){
d_l[v]=val;
}else{
int tm=(tl+tr)/2;
if(pos<=tm){
update_l(2*v,tl,tm,pos,val);
}else{
update_l(2*v+1,tm+1,tr,pos,val);
}
d_l[v]=mi(d_l[2*v],d_l[2*v+1]);
}
}
void update_r(int v,int tl,int tr,int pos,int val){
if(tl==pos and tr==pos){
// cout<<v<<" "<<tr<<" "<<val.ff<<" "<<val.ss<<endl;
d_r[v]=val;
// cout<<d_r[v].ff<<" "<<d_r[v].ss<<endl;
}else{
int tm=(tl+tr)/2;
if(pos<=tm){
update_r(2*v,tl,tm,pos,val);
}else{
update_r(2*v+1,tm+1,tr,pos,val);
}
d_r[v]=mx(d_r[2*v],d_r[2*v+1]);
}
}
void build(int v,int tl,int tr){
if(tl==tr){
d_l[v]=n+1;
d_r[v]=0;
}else{
int tm=(tl+tr)/2;
build(2*v,tl,tm);
build(2*v+1,tm+1,tr);
d_l[v]=n+1;
d_r[v]=0;
}
}
int main(){
t=1;
// cin>>t;
while(t--){
scanf("%d",&n);
build(1,1,2*n);
a[0]=0;
b[0]=0;
b[n+1]=INT_MAX;
a[n+1]=INT_MAX;
for(int i=1;i<=n;i++){
scanf("%d%d",&a[i],&b[i]);
update_l(1,1,2*n,b[i],i);
// l -> a[i];
update_r(1,1,2*n,a[i],i);
// r -> b[i];
// cout<<a[i]<<" "<<b[i]<<" "<<i<<endl;
}
ans=1;
for(int i=1;i<=n;i++){
if(vis[i]==0){
ans*=2;
ans%=mod;
queue <int> q;
q.push(i);
vis[i]=1;
update_l(1,1,2*n,b[i],n+1);
update_r(1,1,2*n,a[i],0);
while(!q.empty()){
auto x=q.front();
q.pop();
while(true){
auto k=query_l(1,1,2*n,a[x]+1,b[x]-1);
// cout<<k.ff<<" "<<k.ss<<" l "<<x<<endl;
// if(k==0){
// cout<<"YES1 "<<i<<" "<<x<<endl;
// return 0;
// }
if(a[k]<a[x]){
q.push(k);
vis[k]=3-vis[x];
update_l(1,1,2*n,b[k],n+1);
update_r(1,1,2*n,a[k],0);
}else{
break;
}
}
// cout<<"HERE "<<i<<" "<<x<<endl;
// if(i==2){
// return 0;
// }
while(true){
auto k=query_r(1,1,2*n,a[x]+1,b[x]-1);
// cout<<k.ff<<" "<<k.ss<<" r "<<x<<endl;
if(k>=n+1){
cout<<"YES"<<endl;
return 0;
}
if(b[k]>b[x]){
q.push(k);
vis[k]=3-vis[x];
update_l(1,1,2*n,b[k],n+1);
update_r(1,1,2*n,a[k],0);
}else{
break;
}
}
}
}
}
for(int i=1;i<=n;i++){
c[a[i]]=i;
c[b[i]]=-i;
}
stack <int> st[2];
for(int i=1;i<=2*n;i++){
// cout<<vis[abs(c[i])]-1<<" "<<i<<endl;
if(c[i]>0){
st[vis[c[i]]-1].push(c[i]);
}else{
if(st[vis[-c[i]]-1].top()!=abs(c[i])){
cout<<0<<endl;
return 0;
}
st[vis[-c[i]]-1].pop();
}
}
printf("%d",ans);
}
}
