#include <bits/stdc++.h>
#define int long long
#define all(x) x.begin(),x.end()
#define LOCAL 0
std::mt19937_64 rng(6994031);
#define UNUSED -1
const int N_MAX=200'000;
const int mod=1e9+7;
using i64=long long;
namespace solve_normal
{
int viz[N_MAX];
std::vector<int>adj[N_MAX];
struct Aib
{
int n;
std::vector<int>maxx;
int lsb(int x)
{
return x&(-x);
}
void update(int poz,int val)
{
for(int i=poz;i<=n;i+=lsb(i))
{
maxx[i]=std::max(maxx[i] , val);
}
}
int query(int poz)
{
int rez=0;
for(int i=poz;i>0;i-=lsb(i))
{
rez=std::max(rez , maxx[i]);
}
return rez;
}
void init(int n)
{
this->n=n;
maxx=std::vector<int>(n+1,0);
}
};
struct interval
{
int l,r,rezl,rezr,index;
};
void dfs(int nod,int val)
{
if(viz[nod]!=-1)
{
return;
}
viz[nod]=val;
for(auto &c:adj[nod])
{
dfs(c,val^1);
}
}
int solve()
{
#if LOCAL
auto __file = freopen("input.txt","r",stdin);
#endif
std::ios::sync_with_stdio(false);
std::cin.tie(0);
int n;
std::cin>>n;
for(int i=0;i<n;i++)
{
adj[i].clear();
viz[i]=-1;
}
std::vector<interval>a(n);
std::vector<i64>cash(2*n+1);
int idk=0;
for(auto &c:a)
{
std::cin>>c.l>>c.r;
cash[c.l]=cash[c.r]=rng();
c.index=idk++;
}
int rez=1;
std::set<int>mp;
mp.insert(0);
for(int i=1;i<=2*n;i++)
{
cash[i]^=cash[i-1];
if(mp.count(cash[i]))
{
rez*=2;
rez%=mod;
}
mp.insert(cash[i]);
}
std::sort(all(a) , [&](interval x,interval y){
return x.l<y.l;
});
Aib aib;
aib.init(2*n);
for(auto &c:a)
{
c.rezl=aib.query(c.r);
aib.update(c.r,c.r);
}
std::set<std::pair<int,int>>mpp;
for(auto &c:a)
{
auto it=mpp.lower_bound({c.l,-1});
std::vector<std::pair<int,int>>aux;
while(it!=mpp.end() && it->first<=c.r)
{
aux.push_back(*it);
//std::cout<<std::min(c.index,it->second)<<' '<<std::max(c.index,it->second)<<'\n';
adj[c.index].push_back(it->second);
adj[it->second].push_back(c.index);
it++;
}
for(auto &v:aux)
{
mpp.erase(v);
}
mpp.insert({c.r , c.index});
}
mpp.clear();
std::sort(all(a) , [&](interval x,interval y){
return x.r>y.r;
});
aib.init(2*n);
for(auto &c:a)
{
c.rezr=2*n-aib.query(2*n-c.l+1)+1;
aib.update(2*n-c.l+1 , 2*n-c.l+1);
}
for(auto &c:a)
{
auto it=mpp.lower_bound({-c.r,-1});
std::vector<std::pair<int,int>>aux;
while(it!=mpp.end() && -it->first>=c.l)
{
aux.push_back(*it);
///std::cout<<std::min(c.index,it->second)<<' '<<std::max(c.index,it->second)<<'\n';
adj[c.index].push_back(it->second);
adj[it->second].push_back(c.index);
it++;
}
for(auto &v:aux)
{
mpp.erase(v);
}
mpp.insert({-c.l , c.index});
}
mpp.clear();
///std::cout<<'\n';
for(auto &c:a)
{
rez*=(c.rezl<=c.rezr);
}
for(int i=0;i<n;i++)
{
if(viz[i]==-1)
{
dfs(i,0);
}
}
for(int i=0;i<n;i++)
{
for(auto &c:adj[i])
{
if(viz[i]==viz[c])
{
rez=0;
}
}
}
#if LOCAL
fclose(__file);
#endif
///std::cerr<<"wtff";
return rez;
}
}
namespace solve_brut
{
bool intersect(std::pair<int,int>a,std::pair<int,int>b)
{
if(a.first>b.first)
{
std::swap(a,b);
}
return b.first<=a.second && a.second<=b.second;
}
int viz[N_MAX];
std::vector<int>adj[N_MAX];
void dfs(int nod,int val)
{
if(viz[nod]!=-1)
{
return;
}
viz[nod]=val;
for(auto &c:adj[nod])
{
dfs(c,val^1);
}
}
int solve()
{
auto __file = freopen("input.txt","r",stdin);
std::ios::sync_with_stdio(false);
std::cin.tie(0);
int n;
std::cin>>n;
for(int i=0;i<n;i++)
{
adj[i].clear();
}
std::vector<std::pair<int,int>>a(n);
for(auto &c:a)
{
std::cin>>c.first>>c.second;
}
std::sort(all(a));
// for(auto &c:a)
// {
// std::cout<<c.first<<' '<<c.second<<'\n';
// }
///std::cerr<<n<<'\n';
for(int i=0;i<n;i++)
{
for(int j=i+1;j<n;j++)
{
if(intersect(a[i] , a[j]))
{
///std::cout<<i<<' '<<j<<'\n';
adj[i].push_back(j);
adj[j].push_back(i);
}
}
}
///std::cerr<<"x0x";
int rez=1;
std::vector<i64>cash(2*n+1);
for(auto &c:a)
{
cash[c.first]=cash[c.second]=rng();
}
std::set<int>mp;
mp.insert(0);
for(int i=1;i<=2*n;i++)
{
cash[i]^=cash[i-1];
if(mp.count(cash[i]))
{
rez*=2;
rez%=mod;
}
mp.insert(cash[i]);
}
std::fill(viz,viz+n,-1);
for(int i=0;i<n;i++)
{
if(viz[i]==-1)
{
dfs(i,0);
}
}
for(int i=0;i<n;i++)
{
for(auto &c:adj[i])
{
if(viz[i]==viz[c])
{
rez=0;
}
}
}
fclose(__file);
return rez;
}
}
void normal()
{
///NU UITA INPUT SUS
std::cout<<solve_normal::solve();
exit(0);
}
int range(int l,int r)
{
return l+rng()%(r-l+1);
}
signed main()
{
normal();
//std::cout<<solve_brut::solve();
//std::cout<<solve_normal::solve();//<<' '<<solve_brut::solve()<<'\n';
//return 0;
while(true)
{
std::ofstream fout("input.txt");
int n=range(5,15'00);
std::vector<int>a(2*n);
std::iota(all(a) , 0);
std::shuffle(all(a) , rng);
fout<<n<<'\n';
for(auto &c:a)
{
c/=2;
assert(c>=0 && c<n);
}
std::vector<std::vector<int>>pii(n);
for(int i=0;i<2*n;i++)
{
pii[a[i]].push_back(i+1);
}
for(auto &c:pii)
{
for(auto &v:c)
{
fout<<v<<' ';
}
fout<<'\n';
}
//std::cin.get();
fout.close();
if(solve_normal::solve()!=solve_brut::solve())
{
break;
}
std::cerr<<"DA";
///std::cerr<<n<<'\n';
}
}
/*
6
2 5
3 12
4 7
6 11
1 10
8 9
prima sortare
1 10
2 5
3 12
4 7
6 11
8 9
graful este de fapt
0 2
0 4
1 2
1 3
3 4
10
4 11
13 14
16 19
6 20
7 8
2 15
5 9
3 12
1 18
10 17
6
3 6
5 8
2 12
1 9
4 11
7 10
6
1 8
10 11
6 7
3 4
2 5
9 12
*/
