#include <bits/stdc++.h>
#define pii pair<int,int>
#define ff first
#define ss second
using namespace std;
const int MAXN = 1000000;
const int MOD = 1e9+7;
int n;
int s, t;
int arr[MAXN*2+1];
pii ord[MAXN+1];
deque <int> stk[2];
int cnt[MAXN+1];
int ans = 1;
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0);
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> s >> t;
arr[s] = arr[t] = i;
ord[i].ff = s;
ord[i].ss = t;
}
for (int i = 1; i <= 2*n; i++) {
int id = arr[i];
if (ord[id].ff == i) {
bool flag = false;
for (int j = 0; j < 2; j++) {
if (!stk[j].size() || ord[stk[j].back()].ss > ord[id].ss) {
stk[j].push_back(id);
flag = true;
}
}
if (!flag) {
ans = ans * 2 % MOD;
while (stk[0].size() && ord[stk[0].back()].ss < ord[id].ss)
stk[0].pop_back();
stk[0].push_back(id);
}
} else {
for (int j = 0; j < 2; j++) {
if (stk[j].size() && stk[j].back() == id) {
cnt[id]++;
stk[j].pop_back();
}
}
}
}
for (int i = 1; i <= n; i++)
ans = ans * cnt[i] % MOD;
cout << ans << '\n';
}
