#include<iostream>
#include<stdio.h>
#include<vector>
#include<cmath>
#include<queue>
#include<string.h>
#include<map>
#include<set>
#include<algorithm>
#define ll long long
#define pi pair < ll,ll >
#define mp(a,b) make_pair(a,b)
#define mid (low+high)/2
#define rep(i,a,b) for(int i = a;i < b;i++)
#define N 300004
#define INF 1e9+7
using namespace std;
ll n,mod=1e9+7;
pi ar[N];
ll seg[4*N][2];
ll lazy[4*N][2];
void relax(ll low,ll high,ll pos,ll id)
{
if(lazy[pos][id])
{
seg[pos][id]+=lazy[pos][id];
if(low != high)
{
lazy[pos*2+1][id]+=lazy[pos][id];
lazy[pos*2+2][id]+=lazy[pos][id];
}
lazy[pos][id]=0;
}
return;
}
void update(ll low,ll high,ll pos,ll slow,ll shigh,ll id)
{
relax(low,high,pos,id);
if(low>=slow&&high<=shigh)
{
lazy[pos][id]++;
relax(low,high,pos,id);
return;
}
if(low>shigh||high<slow)
return;
update(low,mid,pos*2+1,slow,shigh,id);
update(mid+1,high,pos*2+2,slow,shigh,id);
seg[pos][id]=seg[pos*2+1][id]+seg[pos*2+2][id];
return;
}
ll query(ll low,ll high,ll pos,ll slow,ll id)
{
relax(low,high,pos,id);
if(low==high&&low==slow)
return seg[pos][id];
if(low>slow||high<slow)
return 0;
return query(low,mid,pos*2+1,slow,id)+query(mid+1,high,pos*2+2,slow,id);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
rep(i,0,n)
{
cin >> ar[i].first >> ar[i].second;
}
sort(ar,ar+n);
ll ans = 1;
rep(i,0,n)
{
ll q1_left = query(0,2*n,0,ar[i].first,0);
ll q1_right = query(0,2*n,0,ar[i].second,0);
ll q2_left = query(0,2*n,0,ar[i].first,1);
ll q2_right = query(0,2*n,0,ar[i].second,1);
// cout << i << ": " << q1_left << " " << q1_right << " " << q2_left << " " << q2_right << " ";
if(q1_left != q1_right && q2_left != q2_right)
{
ans = 0;
}
else if(q1_left != q1_right)
{
// cout << "upd q2";
update(0,2*n,0,ar[i].first,ar[i].second,1);
}
else if(q2_left != q2_right)
{
// cout << "upd q1";
update(0,2*n,0,ar[i].first,ar[i].second,0);
}
else
{
// cout << "both, upd q1";
update(0,2*n,0,ar[i].first,ar[i].second,0);
ans = (ans*2)%mod;
}
// cout << endl;
}
cout << ans;
return 0;
}
