// In the Name of Allah
#include<bits/stdc++.h>
#define double long double
typedef long long ll;
const ll MAX_N = 2e6+100;
const ll MOD = 1e9+7;
using namespace std;
vector<int> seg[MAX_N*3][2];
pair<int,int> lr[MAX_N];
int a[MAX_N];
int b[MAX_N];
int p[MAX_N];
vector<int> g[MAX_N];
vector<int> vc;
int mark[MAX_N];
int cl[MAX_N];
int n,cnt;
void no(){
cout << 0;
exit(0);
}
void dfs(int v){
mark[v]++;
for(auto x:g[v]){
if (mark[x]){
if (cl[x]==cl[v])
no();
}
else{
cl[x] = 3-cl[v];
dfs(x);
}
}
}
void build(int k,int l,int r){
if (l==r){
if (a[l])
seg[k][0].push_back(a[l]);
if (b[l])
seg[k][1].push_back(b[l]);
return;
}
int mid = (l+r)/2;
build(k*2,l,mid);
build(k*2+1,mid+1,r);
for(int i = 0;i<2;++i){
int lc = k*2;
int rc = lc+1;
seg[k][i].resize(seg[lc][i].size()+seg[rc][i].size());
merge(seg[lc][i].begin(),seg[lc][i].end(),seg[rc][i].begin(),seg[rc][i].end(),seg[k][i].begin());
}
}
void ask(int l,int r,int a,int b,int k,int fl){
if (r<a or b<l)
return;
if (a<=l and r<=b){
if (fl==0){
for(auto x:seg[k][0]){
if (x>=a)
return;
vc.push_back(x);
}
}
else
{
for(int i = seg[k][1].size()-1;i>=0;--i){
int x = seg[k][1][i];
if (x<=b)
return;
vc.push_back(x);
}
}
return;
}
int mid = (l+r)/2;
ask(l,mid,a,b,k*2,fl);
ask(mid+1,r,a,b,k*2+1,fl);
}
int main()
{
cin >> n;
for(int i = 1;i<=n;++i)
scanf("%d%d",&lr[i].first,&lr[i].second);
for(int i = 1;i<=n;++i){
b[lr[i].first] = lr[i].second;
a[lr[i].second] = lr[i].first;
p[lr[i].second] = p[lr[i].first] = i;
}
build(1,1,2*n);
for(int i = 1;i<=n;++i){
vc.clear();
ask(1,2*n,lr[i].first,lr[i].second,1,0);
if (vc.size()){
sort(vc.begin(),vc.end());
for(int j = 0;j<vc.size()-1;j++)
{
int x = vc[j];
int y = vc[j+1];
if (b[y]>b[x])
no();
}
for(auto x:vc)
g[i].push_back(p[x]);
}
vc.clear();
ask(1,2*n,lr[i].first,lr[i].second,1,1);
if (vc.size()){
sort(vc.begin(),vc.end());
for(int j = 0;j<vc.size()-1;j++){
int x = vc[j];
int y = vc[j+1];
if (a[y]>a[x])
no();
}
}
for(auto x:vc)
g[i].push_back(p[x]);
}
for(int i = 1;i<=n;++i){
if (mark[i])
continue;
cnt++;
dfs(i);
}
ll ans = 1;
while(cnt--)
ans *= 2,ans %= MOD;
cout << ans;
return 0;
}
