#include <iostream>
#include <iomanip>
#include <fstream>
#include <vector>
#include <array>
#include <algorithm>
#include <utility>
#include <map>
#include <queue>
#include <set>
#include <cmath>
#include <cstdio>
#include <cstring>
#define ll long long
#define ld long double
#define eps 1e-8
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFLL 0x3f3f3f3f3f3f3f3f
// change if necessary
#define MAXN 1000010
using namespace std;
int n;
pair<int, int> pts[MAXN];
int left_inv[2 * MAXN];
int right_inv[2 * MAXN];
int lmost[MAXN];
int rmost[MAXN];
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for (int i = 1; i <= n; i++) {
int a, b; cin >> a >> b;
pts[i] = {a, b};
left_inv[a] = i;
right_inv[b] = i;
}
set<int> left, right;
for (int i = 1; i <= 2 * n; i++) {
if (left_inv[i]) {
int c = left_inv[i];
if (right.empty()) {
rmost[c] = 0;
} else {
auto it = right.lower_bound(pts[c].second);
if (it == right.begin()) {
rmost[c] = 0;
} else {
rmost[c] = *prev(it);
}
}
left.insert(pts[c].first);
right.insert(pts[c].second);
} else {
int c = right_inv[i];
left.erase(pts[c].first);
right.erase(pts[c].second);
if (left.empty()) {
lmost[c] = INF;
} else {
auto it = left.upper_bound(pts[c].first);
if (it == left.end()) {
lmost[c] = INF;
} else {
lmost[c] = *it;
}
}
}
}
for (int i = 1; i <= n; i++) {
if (lmost[i] < rmost[i]) {
cout << "0\n";
return 0;
}
}
vector<int> stack;
int ans_p = n;
for (int i = 1; i <= 2 * n; i++) {
if (left_inv[i]) {
stack.push_back(left_inv[i]);
} else {
auto it = find(stack.begin(), stack.end(), right_inv[i]);
ans_p -= stack.end() - it - 1;
stack.erase(it);
}
}
ll ans = 1;
for (int i = 0; i < ans_p; i++) {
ans += ans;
if (ans >= MOD) ans -= MOD;
}
cout << ans << '\n';
return 0;
}
