#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <limits>
#include <string>
#include <cassert>
using namespace std;
typedef long long LL;
typedef pair<int,int> pii;
#define forup(i,a,b) for(int i=a; i<b; ++i)
#define fordn(i,a,b) for(int i=a; i>b; --i)
#define rep(i,a) for(int i=0; i<a; ++i)
#define dforup(i,a,b) for(i=a; i<b; ++i)
#define dfordn(i,a,b) for(i=a; i>b; --i)
#define drep(i,a) for(i=0; i<a; ++i)
#define slenn(s,n) for(n=0; s[n]!=13 and s[n]!=0; ++n);s[n]=0
#define gi(x) scanf("%d",&x)
#define gl(x) cin>>x
#define gd(x) scanf("%lf",&x)
#define gs(x) scanf("%s",x)
#define pis(x) printf("%d ",x)
#define pin(x) printf("%d\n",x)
#define pls(x) cout<<x<<" "
#define pln(x) cout<<x<<"\n"
#define pds(x) printf("%.12f ",x)
#define pdn(x) printf("%.12f\n",x)
#define pnl() printf("\n")
#define fs first
#define sc second
#define pb push_back
const int inv=1000000000;
const int minv=-inv;
// BIT struct
struct BIT
{
int bn; //bn>0
vector<int> bA;
BIT(){ bn=0; }
BIT(int bn_){ bn=bn_; bA.resize(bn+1); fill(bA.begin(),bA.end(),0); }
int prefix(int bposn)
{
if(bposn<=0) return 0;
if(bposn>bn) bposn=bn;
int ret=0;
for(int i=bposn; i>0; i-=((i)&(-i)))
ret+=bA[i];
return ret;
}
void update(int bposn, int bincr)
{
if(bposn<=0) return;
if(bposn>bn) return;
for(int i=bposn; i<=bn; i+=((i)&(-i)))
bA[i]+=bincr;
}
int query(int bl, int br)
{
if(bl>br) return 0;
return (prefix(br)-prefix(bl-1));
}
};
// End of BIT struct
const int max_n=1000000+5;
const int modref=((int)(1e9))+7;
int n;
pii e[2*max_n+1];
int d[2*max_n+1];
int r[max_n];
int res;
stack<int> S;
BIT bit[2];
int main()
{
gi(n);
int a,b;
rep(i,n)
{
gi(a); gi(b);
e[a]=pii(0,i);
e[b]=pii(1,i);
d[b]=a;
}
res=1;
fill(r,r+n,-1);
rep(k,2)
bit[k]=BIT(2*n);
forup(j,1,2*n+1)
{
int t=e[j].fs;
int i=e[j].sc;
if(t==0)
{
S.push(j);
continue;
}
if(r[i]!=-1)
{
if(bit[r[i]].query(d[j]+1,j-1)>0)
{
res=0;
continue;
}
bit[r[i]].update(j,-1);
}
else
{
int open=0;
int openk;
rep(k,2)
if(bit[k].query(d[j]+1,j-1)==0)
{
++open;
openk=k;
}
if(open==0)
{
res=0;
continue;
}
else if(open==2)
{
res*=2;
res%=modref;
}
r[i]=openk;
}
while((not S.empty()) and S.top()>=d[j])
{
if(S.top()!=d[j])
{
r[e[S.top()].sc]=1-r[i];
bit[1-r[i]].update(S.top(),1);
}
S.pop();
}
}
pin(res);
return 0;
}
