// :)
// "Khodaya, be man "Tagwaye setiz" biamooz ta
// dar anbuh masuliat nalaghzam ..." -Shariati
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define F first
#define S second
#define MP make_pair
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>;
template <typename T> using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int64;
typedef pair<int,int> pii;
typedef pair<int64,int64> pii64;
const int maxn = 2e6+9;
const int64 M = 1e9+7;
const int64 I = 1e9;
vector <pii> v1;
int fen[2][maxn];
int n, ans = 1;
void upd (int x, int val, int id) {
for (; x < maxn; x += x&-x)
fen[id][x] += val;
return;
}
int get (int x, int id) {
int res = 0;
for (; x; x -= x&-x)
res += fen[id][x];
return res;
}
int main () {
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n;
for (int i = 0; i < n; i++) {
int st, en;
cin >> st >> en;
v1.push_back( MP( en, st ) );
}
sort(v1.begin(), v1.end());
for (int i = 0; i < n; i++) {
int x = v1[i].S, y = v1[i].F;
int cur1 = get(x, 0);
int cur2 = get(x, 1);
if (cur1 + cur2 == 0) {
ans = 2LL * ans % M;
upd(x, 1, 0);
upd(y, -1, 0);
continue;
}
if (cur1 > 0 && cur2 > 0)
ans = 0;
if (cur1 > 0) {
upd(x, 1, 1);
upd(y, -1, 1);
} else {
upd(x, 1, 0);
upd(y, -1, 0);
}
}
cout << ans << "\n";
}
