#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n; cin >> n;
vector<int> s[2];
int l[n+1], r[n+1], event[2*n+1];
for (int i = 1; i <= n; i++) {
cin >> l[i] >> r[i];
event[l[i]] = i;
event[r[i]] = -i;
}
int ans = 1;
for (int i = 1; i <= 2*n; i++) {
int ind = abs(event[i]);
if (event[i] < 0) {
for (auto& st : s) {
if (!st.empty() && st.back() == ind) {
st.pop_back();
}
}
continue;
}
vector<int> opt;
for (int j = 0; j < 2; j++) {
if (s[j].empty() || r[ind] < r[s[j].back()]) {
opt.push_back(j);
}
}
ans = ans*opt.size() % 1'000'000'007;
if (opt.empty()) {
cout << 0;
return 0;
}
s[opt[0]].push_back(ind);
}
cout << ans;
}
