/*
IN THE NAME OF GOD
*/
#include <bits/stdc++.h>
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef long double ld;
#define F first
#define S second
#define Mp make_pair
#define pb push_back
#define pf push_front
#define size(x) ((ll)x.size())
#define all(x) (x).begin(),(x).end()
#define kill(x) cout << x << '\n', exit(0);
#define fuck(x) cout << "(" << #x << " , " << x << ")" << endl
#define endl '\n'
const int N = 1e6+23, lg = 21;
ll Mod = 1e9+7; //998244353;
inline ll MOD(ll a, ll mod=Mod) {a%=mod; (a<0)&&(a+=mod); return a;}
inline ll poww(ll a, ll b, ll mod=Mod) {
ll ans = 1;
a=MOD(a, mod);
while (b) {
if (b & 1) ans = MOD(ans*a, mod);
b >>= 1;
a = MOD(a*a, mod);
}
return ans;
}
int n, par[N], sz[N], val[N], vis[N], a[N], b[N];
int who[2*N], seg[2][5*N], cnt;
int getPar(int v) {return (par[v]==0 ? v : getPar(par[v]));}
int getVal(int v) {return (par[v]==0 ? val[v] : val[v]^getVal(par[v]));}
void merge(int v, int u) {
if(getPar(v)==getPar(u)) {
if(getVal(v) == getVal(u)) kill(0);
return;
}
int x = (getVal(v) == getVal(u));
v=getPar(v), u=getPar(u);
if(sz[v] < sz[u]) swap(v, u);
sz[v] += sz[u];
par[u]=v;
if(x==1) val[u] ^= 1;
cnt--;
}
void build(int ind=1) {
if(ind >= (1<<lg)) {
int id = ind-(1<<lg)+1;
if(id <= 2*n) {
if(a[who[id]]==id) seg[0][ind] = who[id];
else seg[1][ind] = who[id];
}
return;
}
build(2*ind); build(2*ind+1);
if(seg[0][2*ind]==0 || b[seg[0][2*ind]] < b[seg[0][2*ind+1]]) seg[0][ind] = seg[0][2*ind+1];
else seg[0][ind] = seg[0][2*ind];
if(seg[1][2*ind]==0 || (seg[1][2*ind+1]>0 && a[seg[1][2*ind]]>a[seg[1][2*ind+1]])) seg[1][ind] = seg[1][2*ind+1];
else seg[1][ind] = seg[1][2*ind];
}
void upd0(int ind, int val) {
if(ind == 0) return;
if(ind >= (1<<lg)) {
seg[0][ind] = val;
} else {
if(seg[0][2*ind]==0 || b[seg[0][2*ind]] < b[seg[0][2*ind+1]]) seg[0][ind] = seg[0][2*ind+1];
else seg[0][ind] = seg[0][2*ind];
}
upd0(ind/2, val);
}
void upd1(int ind, int val) {
if(ind == 0) return;
if(ind >= (1<<lg)) {
seg[1][ind] = val;
} else {
if(seg[1][2*ind]==0 || (seg[1][2*ind+1]>0 && a[seg[1][2*ind]]>a[seg[1][2*ind+1]])) seg[1][ind] = seg[1][2*ind+1];
else seg[1][ind] = seg[1][2*ind];
}
upd1(ind/2, val);
}
int qry0(int l, int r, int ind=1, int lc=1, int rc=(1<<lg)+1) {
if(l>=rc || lc>=r) return 0;
if(lc>=l && rc<=r) return seg[0][ind];
int mid = (lc+rc)/2;
int x=qry0(l, r, 2*ind, lc, mid), y=qry0(l, r, 2*ind+1, mid, rc);
if(b[y] > b[x]) return y;
return x;
}
int qry1(int l, int r, int ind=1, int lc=1, int rc=(1<<lg)+1) {
if(l>=rc || lc>=r) return 0;
if(lc>=l && rc<=r) return seg[1][ind];
int mid = (lc+rc)/2;
int x=qry1(l, r, 2*ind, lc, mid), y=qry1(l, r, 2*ind+1, mid, rc);
if(x==0 || (a[y] < a[x] && y>0)) return y;
return x;
}
void dfs(int v) {
vis[v] = 1;
upd0(a[v]+(1<<lg)-1, 0);
upd1(b[v]+(1<<lg)-1, 0);
while(true) {
int u = qry0(a[v], b[v]);
if(u==0 || b[u]<b[v]) break;
merge(v, u);
dfs(u);
}
while(true) {
int u = qry1(a[v], b[v]);
if(u==0 || a[u]>a[v]) break;
merge(v, u);
dfs(u);
}
}
int main () {
ios_base::sync_with_stdio(false), cin.tie(0);
cin>>n; cnt=n;
fill(sz+1, sz+n+1, 1);
for(int i=1; i<=n; i++) {
cin>>a[i]>>b[i];
who[a[i]] = who[b[i]] = i;
}
build(1);
for(int i=1; i<=n; i++) {
if(vis[i] == 1) continue;
dfs(i);
}
vector<pii> vec[2];
for(int i=1; i<=n; i++) {
vec[getVal(i)].pb({a[i], b[i]});
}
for(int i=0; i<2; i++) {
sort(all(vec[i]));
set<int> st;
for(auto it : vec[i]) {
auto it2 = st.lower_bound(it.F);
if(it2!=st.end() && (*it2) < it.S) kill(0);
st.insert(it.S);
}
}
cout<<poww(2, cnt);
return 0;
}
