#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
const ll MOD=1e9+7;
const ll MOD2=998244353;
const ll N=2e6+5;
const ld pi=3.14159265359;
const ll INF=(1LL<<60);
#define SQ(i) ((i)*(i))
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define setp setprecision
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()
ll n,d1[N],d2[N],a[N],b[N],to[N],col[N],ans=1;
vector<ll> v[N];
ll f1(ll id){
return (id==d1[id]?id:d1[id]=f1(d1[id]));
}
ll f2(ll id){
return (id==d2[id]?id:d2[id]=f2(d2[id]));
}
void DFS(ll id){
for(auto i:v[id]){
if(col[i]){
if(col[i]==col[id])ans=0;
continue;
}
col[i]=3-col[id];
DFS(i);
}
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n;
REP1(i,2*n+1)d1[i]=d2[i]=i;
REP1(i,n){
cin>>a[i]>>b[i];
to[a[i]]=to[b[i]]=i;
d1[b[i]]=b[i]+1;
}
REP1(i,2*n){
if(b[to[i]]==i){
ll lst=0;
for(ll j=f1(a[to[i]]+1);j<=i;j=f1(j+1)){
j=f2(j);
v[to[i]].pb(to[j]);v[to[j]].pb(to[i]);
if(lst)d2[lst]=j;
lst=j;
}
d1[a[to[i]]]=a[to[i]]+1;
}
}
REP1(i,n){
if(col[i]==0){
col[i]=1;
DFS(i);
ans=ans*2%MOD;
}
}
cout<<ans<<"\n";
return 0;
}
