/*
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*/
#include <bits/stdc++.h>
//#pragma GCC optimize("O3")
//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")
//#pragma GCC target("avx,tune=native")
//float __attribute__((aligned(32)))
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
int mysqrt(ll x){
int l = 0, r = 1e9 + 1;
while (r - l > 1){
int m = (l + r) / 2;
if (m * (ll)m <= x)
l = m;
else
r = m;
}
return l;
}
mt19937 rnd(1337);
ll AR = 19, BR = 13, CR = 23, XR = 228, YR = 322, MODR = 1e9 + 993;
ll myrand(){
ll ZR = (XR * AR + YR * BR + CR) % MODR;
XR = YR;
YR = ZR;
return ZR;
}
const int Mod = 1e9 + 7;
int bpow(int x, int y){
if (y == 0)
return 1;
if (y == 1)
return x;
int ret = bpow(x, y >> 1);
ret = (ret * (ll)ret) % Mod;
if (y & 1)
ret = (ret * (ll)x) % Mod;
return ret;
}
int bdiv(int x, int y){
return (x * (ll)bpow(y, Mod - 2)) % Mod;
}
void setmin(int &x, int y){
x = min(x, y);
}
void setmax(int &x, int y){
x = max(x, y);
}
void setmin(ll &x, ll y){
x = min(x, y);
}
void setmax(ll &x, ll y){
x = max(x, y);
}
int gcd(int a, int b){
return a ? gcd(b % a, a) : b;
}
const ll llinf = 2e18 + 100;
const int maxn = 2e5 + 100, maxw = 1e6 + 100, inf = 2e9 + 100, sq = 300, mod = 1e9 + 7, LG = 17;
pair<int, int> a[maxw];
int arr[2 * maxw];
int n;
vector<pair<int, int> > w;
int p[maxw];
int r[maxw];
int get(int x){
return x == p[x] ? x : p[x] = get(p[x]);
}
void uni(int x, int y){
x = get(x);
y = get(y);
if (x == y)
return;
if (r[x] < r[y])
swap(x, y);
p[y] = x;
if (r[x] == r[y])
r[x]++;
}
bool used[maxw];
vector<int> e[maxw];
int col[maxw];
bool dfs(int v, int cs = 0){
col[v] = cs;
used[v] = 1;
for (auto i : e[v])
if (!used[i]){
if (dfs(i, cs ^ 1))
return 1;
}
else
if (col[i] != (cs ^ 1))
return 1;
return 0;
}
int main()
{
#ifdef ONPC
//ifstream cin("a.in");
//ofstream cout("a.out");
freopen("a.in", "r", stdin);
freopen("a.out", "w", stdout);
#else
//ifstream cin("sprinklers.in");
//ofstream cout("sprinklers.out");
//freopen("road.in", "r", stdin);
//freopen("road.out", "w", stdout);
#endif // ONPC
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n;
for (int i = 0; i < n; i++){
cin >> a[i].first >> a[i].second;
a[i].first--;
a[i].second--;
arr[a[i].first] = i;
arr[a[i].second] = -1;
}
for (int i = 0; i < n; i++)
p[i] = i;
/*
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++)
if (a[i].first < a[j].first && a[i].second > a[j].first && a[i].second < a[j].second)
uni(i, j);
*/
stack<int> q;
stack<int> g;
for (int i = 0; i < 2 * n; i++){
if (arr[i] < 0){
q.pop();
int last = (q.empty() ? inf : a[q.top()].second);
vector<int> vsp;
while (!g.empty() && a[g.top()].second < last)
vsp.push_back(g.top()), g.pop();
reverse(vsp.begin(), vsp.end());
for (auto j : vsp)
q.push(j);
continue;
}
int id = arr[i];
if (!g.empty() && a[id].second > a[g.top()].second){
cout << 0;
return 0;
}
int last = -1;
stack<int> vsp;
while (!q.empty() && a[q.top()].second < a[id].second){
if (last != -1){
if (get(last) == get(q.top()))
break;
uni(last, q.top());
}
else
last = q.top();
vsp.push(q.top());
q.pop();
}
if (last != -1)
w.push_back(make_pair(last, id)), g.push(id);
else
q.push(id);
while (!vsp.empty())
q.push(vsp.top()), vsp.pop();
}
for (auto it : w)
if (get(it.first) == get(it.second)){
cout << 0;
return 0;
}
for (auto it : w)
e[get(it.first)].push_back(get(it.second)), e[get(it.second)].push_back(get(it.first));
int ans = 1;
for (int i = 0; i < n; i++)
if (!used[get(i)])
if (dfs(get(i))){
cout << 0;
return 0;
}
else
ans = (ans * 2) % mod;
cout << ans;
}
