#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define y1 zck_is_king
#define pii pair<int, int>
#define ull unsigned ll
#define f first
#define s second
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define SQ(x) (x)*(x)
#define MN(a,b) a = min(a,(__typeof__(a))(b))
#define MX(a,b) a = max(a,(__typeof__(a))(b))
#define pb push_back
#define REP(i,n) for (int i = 0; i<n; ++i)
#define RREP(i,n) for (int i = n-1; i>=0; --i)
#define REP1(i,n) for (int i = 1; i<=n; ++i)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#ifdef BALBIT
#define IOS()
#define bug(...) fprintf(stderr,"#%d (%s) = ",__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 IOS() ios_base::sync_with_stdio(0);cin.tie(0);
#define endl '\n'
#define bug(...)
#endif
const int iinf = 1e9+10;
const ll inf = 1ll<<60;
const ll mod = 1e9+7 ;
void GG(){cout<<"0\n"; exit(0);}
ll mpow(ll a, ll n, ll mo = mod){ // a^n % mod
ll re=1;
while (n>0){
if (n&1) re = re*a %mo;
a = a*a %mo;
n>>=1;
}
return re;
}
ll inv (ll b, ll mo = mod){
if (b==1) return b;
return (mo-mo/b) * inv(mo%b,mo) % mo;
}
const int maxn = 2e6+5;
int par[maxn];
int find(int x) {return x==par[x]?x:par[x] = find(par[x]);}
int cc = 0;
vector<int> g[maxn];
void mg(int a, int b) {
int A=find(a), B=find(b);
if (A!=B) {
--cc;
par[A] = B;
g[a].pb(b); g[b].pb(a);
bug(a,b);
}
}
int col[maxn];
void dfs(int v) {
for (int u : g[v]) {
if (col[u] == -1) {
col[u] = col[v] ^ 1;
dfs(u);
}
}
}
struct seg{
int l,r,i;
};
int who[maxn];
bool pluck[maxn];
int myl[maxn], myi[maxn];
signed main(){
IOS();
memset(col, -1, sizeof col);
int n; cin>>n;
REP(i,n) par[i] = i;
vector<seg> v;
cc = n;
REP(i,n) {
int a,b; cin>>a>>b;
v.pb({a,b,i});
who[a]=who[b]=i; pluck[b] = 1;
}
REP(hi,2) {
vector<seg>q;
memset(myi, -1, sizeof myi);
for (seg &s : v) {
myl[s.r] = s.l; myi[s.r] = s.i;
}
// sort(ALL(v), [&](seg a, seg b){return a.r < b.r;});
REP1(i,2*n) {
if (myi[i] == -1) continue;
int eye = myi[i], el = myl[i];
while (!q.empty() && q.back().l > el) q.pop_back();
if (!q.empty() && q.back().r > el) {
mg(eye, q.back().i);
// if (q.back().i==0 && v[i].i==2) {
// bug(q.back().r, v[i].l);
// }
// q.back().r = v[i].r; q.back().
// }else{
}
q.pb({el,i,eye});
}
// bug("HO");
for (seg & s : v) {
s.l=2*n+1-s.l; s.r=2*n+1-s.r;
swap(s.l, s.r);
}
}
bug(cc);
REP(i,n) {
if (col[i] == -1) {
col[i] = 0; dfs(i);
}
}
REP(i,n) bug(i, col[i]);
vector<int> s1,s2; s1.pb(-1); s2.pb(-1);
REP1(i,2*n){
if (pluck[i]) {
if (s1.back()==who[i]) s1.pop_back();
else if (s2.back()==who[i]) s2.pop_back();
else GG();
}else{
(col[who[i]]?s1:s2).pb(who[i]);
}
}
cout<<mpow(2,cc)<<endl;
}
