#include <bits/stdc++.h>
using namespace std;
#define finish(x) return cout << x << endl, 0
#define ll long long
const int N = 1000001;
int n, vis[N], p[N], mod = 1e9 + 7;
vector <pair <int, int> > a;
vector <int> f, v[N];
int find(int x){
if(p[x] == x) return x;
return p[x] = find(p[x]);
}
void merge(int x, int y){
x = find(x);
y = find(y);
if(x == y){
if(vis[x] == vis[y]){
cout << 0 << endl;
exit(0);
}
return;
}
p[y] = x;
if(vis[x] == -1 && vis[y] == -1){
v[x].push_back(y);
v[y].push_back(x);
vis[x] = 0;
vis[y] = 1;
return;
}
if(vis[y] == -1) swap(x, y);
if(vis[x] == -1){
v[x].push_back(y);
v[y].push_back(x);
vis[x] = vis[y] ^ 1;
return;
}
if(vis[x] == (vis[y] ^ 1)){
v[x].push_back(y);
v[y].push_back(x);
return;
}
y = v[y][0];
assert(vis[x] == vis[y]);
v[x].push_back(y);
v[y].push_back(x);
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
memset(vis, -1, sizeof vis);
cin >> n;
a.resize(n);
f.resize(2 * n);
for(int i = 0 ; i < n ; i++){
cin >> a[i].first >> a[i].second;
a[i].first--; a[i].second--;
f[a[i].first] = f[a[i].second] = i;
p[i] = i;
}
vector <int> o, del(n);
for(int i = 0 ; i < 2 * n ; i++){
while(o.size() && del[o.back()]){
o.pop_back();
}
if(a[f[i]].first == i){
o.push_back(f[i]);
}
else{
del[f[i]] = 1;
int j = (int)o.size() - 1;
while(o[j] != f[i]){
merge(f[i], o[j]);
j--;
}
}
}
int ans = 1;
for(int i = 0 ; i < n ; i++){
if(find(i) == i){
ans *= 2;
if(ans >= mod) ans -= mod;
}
}
cout << ans << endl;
}
