#pragma GCC diagnostic ignored "-Wmisleading-indentation"
#include <algorithm>
#include <iostream>
#include <numeric>
#include <cstring>
#include <iomanip>
#include <vector>
#include <bitset>
#include <stack>
#include <queue>
#include <cmath>
#include <set>
#include <map>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
const int maxn = 1e6+10;
const int mod = 1e9+7;
const int inf = 1e9+42069;
inline int bpow(int x, int y)
{
int ans = 1;
while(y > 0)
{
if(y & 1)
ans = 1ll*ans*x % mod;
x = 1ll*x*x % mod;
y >>= 1;
}
return ans;
}
int lft[maxn];
int rit[maxn];
int owner[maxn*2];
bool vis[maxn];
vector<int> G[maxn];
bool col[maxn];
#define lc (v<<1)
#define rc (lc|1)
struct mfsgt
{
vector<int> vals;
int (*mf)(int, int);
int n;
int d;
mfsgt(){};
mfsgt(int _n, int (*_mf)(int,int), int _d)
{
mf = _mf;
n = _n;
d = _d;
vals = vector<int>(4*n, d);
}
inline void upd(int v)
{
vals[v] = (*mf)(vals[lc], vals[rc]);
}
void ass(int l, int r, int p, int x, int v)
{
if(r - l == 1)
return (void)(vals[v] = x);
int m = (l+r) / 2;
if(p < m)
ass(l, m, p, x, lc);
else
ass(m, r, p, x, rc);
upd(v);
}
int get(int l, int r, int s, int e, int v)
{
if(e <= l or r <= s) return d;
if(s <= l and r <= e) return vals[v];
int m = (l+r) / 2;
return (*mf)(get(l, m, s, e, lc), get(m, r, s, e, rc));
}
inline void ass(int p, int x)
{
return ass(0, n, p, x, 1);
}
inline int get(int s, int e)
{
return get(0, n, s, e, 1);
}
} mnseg, mxseg;
inline int min(int x, int y)
{
return std::min(x, y);
}
inline int max(int x, int y)
{
return std::max(x, y);
}
inline int getbef(int l, int r) // [l, r)
{
int x = mnseg.get(l, r);
if(x == inf or x >= l) return -1;
return owner[x];
}
inline int getaft(int l, int r)
{
int y = mxseg.get(l, r);
if(y == -1 or y <= r) return -1;
return owner[y];
}
inline int getany(int l, int r)
{
int x = getbef(l, r);
if(x != -1)
return x;
x = getaft(l, r);
return x;
}
void mfdfs(int v, bool c)
{
//cerr << "in " << v << endl;
if(vis[v]) return (void)(cerr << "ridim " << v << endl);
vis[v] = true;
col[v] = c;
mnseg.ass(rit[v], inf);
mxseg.ass(lft[v], -1);
int u = getany(lft[v]+1, rit[v]);
while(u != -1)
{
G[v].push_back(u);
G[u].push_back(v);
mfdfs(u, !c);
u = getany(lft[v]+1, rit[v]);
}
}
int32_t main()
{
ios::sync_with_stdio(false);
cin.tie(0);
int n; cin >> n;
mnseg = mfsgt(2*n, min, inf); // write lft[i] in rit[i] others are inf
mxseg = mfsgt(2*n, max, -1); // write rit[i] in lft[i] others are -1
for(int i = 0; i < n; i++)
{
cin >> lft[i] >> rit[i];
lft[i]--; rit[i]--;
owner[lft[i]] = i;
owner[rit[i]] = i;
mnseg.ass(rit[i], lft[i]);
mxseg.ass(lft[i], rit[i]);
}
//for(int i = 0; i < 2*n; i++) cerr << mnseg.get(i, i+1) << " "; cerr << endl;
//for(int i = 0; i < 2*n; i++) cerr << mxseg.get(i, i+1) << " "; cerr << endl;
int cmpcnt = 0;
for(int i = 0; i < n; i++)
{
if(!vis[i])
{
cmpcnt++;
//cerr << "starting " << i << endl;
mfdfs(i, 0);
}
}
//for(int i = 0; i < n; i++) cerr << col[i] << " "; cerr << endl;
stack<int> mfst[2];
for(int i = 0; i < 2*n; i++)
{
int v = owner[i];
if(i == lft[v])
{
mfst[col[v]].push(v);
}
else
{
if(mfst[col[v]].empty() or mfst[col[v]].top() != v)
{
cout << 0 << endl;
return 0;
}
mfst[col[v]].pop();
}
}
cout << bpow(2, cmpcnt) << endl;
return 0;
}
