#include <bits/stdc++.h>
/*
Two stacks
Ranges intersect -> not on the same stack
Segtree and DSU
Very similar to BOJ 7083
*/
bool possible;
int numccs;
std::vector<int> parents;
std::vector<int> states;
int find(int x){//parent, its state
if(parents[x]==-1)return x;
int fnd=find(parents[x]);
if(fnd!=parents[x]){//fnd is the parent's parent
states[x]^=states[parents[x]];
parents[x]=fnd;
}
return fnd;
}
bool merge(int a,int b){//merging with opposite parity; returns false if cannot
int fa=find(a);
int fb=find(b);
if(fa==fb){
return states[a]!=states[b];
}
numccs--;
states[fb]=states[b]^states[a]^1;
parents[fb]=fa;
return 1;
}
struct segtree{
int size;
std::vector<std::vector<int>> nodes;//it is cleared every time anyway
segtree(int n){
nodes.resize(2*n-1);
size=n;
}
void add(int l,int r,int x,int nl,int nr,int ni){
if(r<=nl||l>=nr)return;
if(l<=nl&&r>=nr){
nodes[ni].push_back(x);
return;
}
int nm=(nl+nr)/2;
add(l,r,x,nl,nm,ni+1);
add(l,r,x,nm,nr,ni+2*(nm-nl));
}
void query(int pos,int val,int nl,int nr,int ni){
if(pos<nl||pos>=nr)return;
for(int i:nodes[ni]){
possible&=merge(i,val);
}
if(nodes[ni].size()>1)nodes[ni].resize(1);//max looked at is 1 as everything was merged
if(nl+1>=nr)return;
int nm=(nl+nr)/2;
query(pos,val,nl,nm,ni+1);
query(pos,val,nm,nr,ni+2*(nm-nl));
}
};
int main(){
std::ios::sync_with_stdio(0);
std::cin.tie(0);
int m;
std::cin>>m;
int n=2*m;
numccs=m;
std::vector<std::pair<int,int>> intervs;
std::vector<int> sinds;
for(int i=0;i<m;i++){
sinds.push_back(i);
int a,b;
std::cin>>a>>b;
a--,b--;
intervs.push_back({std::min(a,b),std::max(a,b)});
}
std::sort(sinds.begin(),sinds.end(),[&](int a,int b){return intervs[a].second<intervs[b].second;});
parents.resize(m,-1);
states.resize(m,0);
segtree st(n);
possible=true;
for(int i=0;i<m;i++){
st.query(intervs[sinds[i]].first,i,0,n,0);
st.add(intervs[sinds[i]].first,intervs[sinds[i]].second,i,0,n,0);
if(!possible)break;
}
long long curnum=1;
long long squ=2;
for(int i=numccs;i;){
if(i&1){
curnum*=squ;
curnum%=1000000007;
}
squ*=squ;
squ%=1000000007;
i/=2;
}
std::cout<<(possible?curnum:0)<<'\n';
}
