#pragma GCC target("avx2")
#include<bits/stdc++.h>
#include<x86intrin.h>
#include<immintrin.h>
//#pragma GCC optimize("unroll-loops")
using namespace std;
#define ll long long
//#define int ll
#define ull unsigned long long
#define ld long double
#define rep(a) rep1(i,a)
#define rep1(i,a) rep2(i,0,a)
#define rep2(i,b,a) for(int i=(b); i<((int)(a)); i++)
#define rep3(i,b,a) for(int i=(b); i>=((int)(a)); i--)
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define pb push_back
#define inf 1010000000
//#define inf 4000000000000000000
#define eps 1e-9
#define sz(a) ((int)a.size())
#define pow2(x) (1ll<<(x))
//#define ceiling(a,b) (((a)+(b)-1)/(b))
#ifdef i_am_noob
#define bug(...) cerr << "#" << __LINE__ << ' ' << #__VA_ARGS__ << "- ", _do(__VA_ARGS__)
template<typename T> void _do(T && x) {cerr << x << endl;}
template<typename T, typename ...S> void _do(T && x, S&&...y) {cerr << x << ", "; _do(y...);}
#else
#define bug(...) 826
#endif
inline char readchar(){
const int maxn=1000000;
static char buf[maxn],*p=buf,*q=buf;
if(p==q&&(q=(p=buf)+fread(buf,1,maxn,stdin))==buf) return EOF;
else return *p++;
}
inline int readint(){
int c=readchar(),x=0,neg=0;
while((c<'0'||c>'9')&&c!='-'&&c!=EOF) c=readchar();
if(c=='-') neg=1,c=readchar();
while(c>='0'&&c<='9') x=(x<<3)+(x<<1)+(c^'0'),c=readchar();
return neg?-x:x;
}
const int Mod=1000000007,Mod2=998244353;
const int MOD=Mod;
const int maxn=1000005;
//i_am_noob
#define v8si __attribute__ (( vector_size(32) )) signed
int val[maxn*8];
void pull(int k){val[k]=max(val[k<<1],val[k<<1|1]);}
void modify(int k, int l, int r, int p, int x){
if(l==r){
val[k]=x;
return;
}
int mid=l+r>>1;
if(p<=mid) modify(k<<1,l,mid,p,x);
else modify(k<<1|1,mid+1,r,p,x);
pull(k);
}
int query(int k, int l, int r, int ql, int qr){
if(l>qr||r<ql) return -inf;
if(ql<=l&&qr>=r) return val[k];
int mid=l+r>>1;
return max(query(k<<1,l,mid,ql,qr),query(k<<1|1,mid+1,r,ql,qr));
}
int par[maxn*2];
bool same[maxn*2];
vector<int> child[maxn*2];
int Find(int x){return par[x]==x?x:par[x]=Find(par[x]);}
void Union(int x, int y){
bug(x,y);
if(sz(child[Find(x)])<sz(child[Find(y)])) swap(x,y);
int a=Find(x),b=Find(y);
if(a==b){
bug(x,y,same[x],same[y]);
if(!(same[x]^same[y])){
cout << "0\n";
exit(0);
}
return;
}
if(!(same[x]^same[y])){
for(auto i: child[b]) same[i]^=1;
}
for(auto i: child[b]) child[a].pb(i);
bug(a);
for(auto i: child[a]) bug(i,same[i]);
child[b].clear();
par[b]=a;
}
int n,a[maxn*2];
void orzck(){
rep(maxn*8) val[i]=-inf;
rep(maxn*2) par[i]=i,child[i].pb(i),same[i]=1;
n=readint();
rep(n){
int x,y;
x=readint(),y=readint();
x--,y--;
a[x]=y,a[y]=x;
}
rep(2*n) if(a[i]<i){
int x=query(1,0,2*n-1,0,a[i]-1);
if(x<a[i]){
modify(1,0,2*n-1,a[i],i);
continue;
}
Union(a[x],a[i]);
modify(1,0,2*n-1,a[x],-inf);
while(1){
int y=query(1,0,2*n-1,0,a[i]-1);
if(y<a[i]) break;
Union(a[y],a[i]);
modify(1,0,2*n-1,a[y],-inf);
}
modify(1,0,2*n-1,a[x],x);
modify(1,0,2*n-1,a[i],i);
}
set<int> st;
rep(2*n) if(a[i]>i) st.insert(Find(i));
int res=1;
rep(sz(st)) res=res*2%MOD;
cout << res << "\n";
}
signed main(){
ios_base::sync_with_stdio(0),cin.tie(0);
#ifdef i_am_noob
freopen("input1.txt","r",stdin);
freopen("output1.txt","w",stdout);
freopen("output2.txt","w",stderr);
#endif
cout << fixed << setprecision(15);
orzck();
return 0;
}
