//Be Name Khoda
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define all(x) x.begin(), x.end()
#define pii pair<int, int>
#define pll pair<ll, ll>
const ll mxn = 1e6 + 16, md = 1e9 + 7;
ll n, m, q;
ll c[2 * mxn], t[2 * mxn];
bool ok[2 * mxn];
vector<ll> a, b;
struct item {
ll mn, mx;
};
struct segtree {
ll sz = 1;
item NE = {2 * mxn, -1};
vector<item> v;
vector<bool> b;
void init(ll n) {
while(sz < n) sz <<= 1;
v.assign(2 * sz, NE);
b.assign(2 * sz, 1);
}
void set_A(int i, ll q, int x, int lx, int rx) {
if(rx - lx == 1) {
v[x].mn = q;
return;
}
int m = (lx + rx) >> 1;
if(i < m) set_A(i, q, 2 * x + 1, lx, m);
else set_A(i, q, 2 * x + 2, m, rx);
v[x].mn = min(v[2 * x + 1].mn, v[2 * x + 2].mn);
return;
}
void set_A(int i, ll q) {
set_A(i, q, 0, 0, sz);
return;
}
void set_B(int i, ll q, int x, int lx, int rx) {
if(rx - lx == 1) {
v[x].mx = q;
return;
}
int m = (lx + rx) >> 1;
if(i < m) set_B(i, q, 2 * x + 1, lx, m);
else set_B(i, q, 2 * x + 2, m, rx);
v[x].mx = max(v[2 * x + 1].mx, v[2 * x + 2].mx);
return;
}
void set_B(int i, ll q) {
set_B(i, q, 0, 0, sz);
return;
}
void set(int i, int x, int lx, int rx) {
if(rx - lx == 1) {
b[x] = 0;
v[x] = NE;
return;
}
int m = (lx + rx) >> 1;
if(i < m) set(i, 2 * x + 1, lx, m);
else set(i, 2 * x + 2, m, rx);
v[x].mx = max(v[2 * x + 1].mx, v[2 * x + 2].mx);
v[x].mn = min(v[2 * x + 1].mn, v[2 * x + 2].mn);
b[x] = b[2 * x + 1] | b[2 * x + 2];
return;
}
void set(int i) {
set(i, 0, 0, sz);
return;
}
pii cal(int l, int r, int x, int lx, int rx) {
if(rx <= l || r <= lx) return {2 * mxn, -1};
if(l <= lx && rx <= r) {
return make_pair(v[x].mn, v[x].mx);
}
int m = (lx + rx) >> 1;
pii ans = cal(l, r, 2 * x + 1, lx, m);
pii ans2 = cal(l, r, 2 * x + 2, m, rx);
ans.first = min(ans.first, ans2.first);
ans.second = max(ans.second, ans2.second);
return ans;
}
pii cal(int l, int r) {
return cal(l, r, 0, 0, sz);
}
pii find_mn(int l, int r, int x, int lx, int rx) {
if(rx <= l || r <= lx) return {2 * mxn, 2 * mxn};
if(rx - lx == 1) {
if(!b[x]) return {2 * mxn, 2 * mxn};
if(v[x].mn < l - 1) return {v[x].mn, lx};
return {2 * mxn, 2 * mxn};
}
if(l <= lx && rx <= r) {
if(v[x].mn >= l - 1) return {2 * mxn, 2 * mxn};
if(!b[x]) return {2 * mxn, 2 * mxn};
int m = (lx + rx) >> 1;
if(v[2 * x + 2].mn < l - 1) return find_mn(l, r, 2 * x + 2, m, rx);
return find_mn(l, r, 2 * x + 1, lx, m);
}
int m = (lx + rx) >> 1;
pii ans = find_mn(l, r, 2 * x + 2, m, rx);
if(ans.second == 2 * mxn) {
ans = find_mn(l, r, 2 * x + 1, lx, m);
}
return ans;
}
pii find_mn(int l, int r) {
return find_mn(l, r, 0, 0, sz);
}
pii find_mx(int l, int r, int x, int lx, int rx) {
if(rx <= l || r <= lx) return {2 * mxn, 2 * mxn};
if(rx - lx == 1) {
if(!b[x]) return {2 * mxn, 2 * mxn};
if(v[x].mx > r) return {v[x].mx, lx};
return {2 * mxn, 2 * mxn};
}
if(l <= lx && rx <= r) {
if(v[x].mx <= r) return {2 * mxn, 2 * mxn};
if(!b[x]) return {2 * mxn, 2 * mxn};
int m = (lx + rx) >> 1;
if(v[2 * x + 1].mx > r) return find_mx(l, r, 2 * x + 1, lx, m);
return find_mx(l, r, 2 * x + 2, m, rx);
}
int m = (lx + rx) >> 1;
pii ans = find_mx(l, r, 2 * x + 1, lx, m);
if(ans.second == 2 * mxn) {
ans = find_mx(l, r, 2 * x + 2, m, rx);
}
return ans;
}
pii find_mx(int l, int r) {
return find_mx(l, r, 0, 0, sz);
}
}; segtree st;
bitset<2 * mxn> mark;
pll p, d;
inline void input() {
cin >> n;
for(int i = 0; i < n; i++) {
cin >> q; q--;
a.push_back(q); ok[q] = 1; c[q] = i;
cin >> q; q--;
b.push_back(q); t[a.back()] = q; c[q] = i;
}
}
inline void BFS(int i) {
vector<ll> bfs;
bfs.push_back(i);
st.set(a[i]); st.set(b[i]);
ll ptr = 0;
while(ptr < int(bfs.size())) {
auto u = bfs[ptr++];
mark.set(a[u]), mark.set(b[u]);
p = {0, 0};
while(p.second != 2 * mxn) {
p = st.find_mx(a[u] + 1, b[u]);
if(p.second == 2 * mxn) break;
bfs.push_back(c[p.second]);
st.set(a[c[p.second]]); st.set(b[c[p.second]]);
} p = {0, 0};
while(p.second != 2 * mxn) {
p = st.find_mn(a[u] + 1, b[u]);
if(p.second == 2 * mxn) break;
bfs.push_back(c[p.second]);
st.set(a[c[p.second]]); st.set(b[c[p.second]]);
}
}
}
inline void solve() {
st.init(2 * n);
for(int i = 0; i < n; i++) {
st.set_A(b[i], a[i]);
st.set_B(a[i], b[i]);
}
for(int i = 0; i < n; i++) {
p = st.find_mn(a[i] + 1, b[i]);
d = st.find_mx(a[i] + 1, b[i]);
if(d.second == 2 * mxn || p.second == 2 * mxn) continue;
if(p.second > d.second && p.first < a[i] && d.first > b[i]) {
cout << "0\n";
return;
}
}
ll ans = 1;
for(int i = 0; i < n; i++) {
if(mark[a[i]]) continue;
BFS(i);
ans *= 2;
ans %= md;
}
cout << ans << endl;
return;
}
int main() {
ios::sync_with_stdio(false); cin.tie(NULL);
input(), solve();
return 0;
}
