#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
using namespace std;
const int N = 1e6 + 5;
const int mod = 1e9 + 7;
vector <pair <int, int>> s[3];
vector <int> adj[N];
pair <int, int> a[N];
int id[2 * N];
int c[N];
int nxt[N];
int par[N];
int n;
int getnxt(int u) {
return (nxt[u] == u || nxt[u] == 0) ? u : (nxt[u] = getnxt(nxt[u]));
}
int getpar(int u) {
return (par[u] < 0) ? u : (par[u] = getpar(par[u]));
}
bool join(int u, int v) {
u = getpar(u);
v = getpar(v);
if (u == v)
return false;
if (par[u] > par[v])
swap(u, v);
par[u] += par[v];
par[v] = u;
return true;
}
void dfs(int u) {
for (int v : adj[u]) {
if (!c[v]) {
c[v] = 3 - c[u];
dfs(v);
} else if (c[u] == c[v]) {
cout << 0;
exit(0);
}
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n;
for (int i = 1; i <= n; i++)
cin >> a[i].fi >> a[i].se;
sort(a + 1, a + n + 1);
for (int i = 1; i <= n; i++) {
id[a[i].fi] = i;
id[a[i].se] = -i;
}
for (int i = 1, cur = 0; i <= 2 * n; i++) {
int u = abs(id[i]);
if (id[i] > 0) {
nxt[u] = u;
par[u] = -1;
cur = u;
} else {
int pos = u;
while (pos <= cur) {
int lo = pos;
int hi = n + 1;
while (hi - lo > 1) {
int mid = (lo + hi) >> 1;
int nxtmid = getnxt(mid);
if (nxtmid <= cur && getpar(nxtmid) == getpar(u))
lo = mid;
else
hi = mid;
}
pos = getnxt(hi);
if (pos <= cur) {
adj[u].push_back(pos);
adj[pos].push_back(u);
assert(join(u, pos));
}
}
nxt[u] = u + 1;
}
}
for (int i = 1; i <= n; i++)
if (!c[i])
c[i] = 1, dfs(i);
for (int i = 1; i <= 2; i++)
s[i].push_back(mp(0, 2 * n + 1));
for (int i = 1; i <= 2 * n; i++) {
int u = abs(id[i]);
if (id[i] < 0)
s[c[u]].pop_back();
else {
if (a[u].se > s[c[u]].back().se)
return cout << 0, 0;
s[c[u]].push_back(a[u]);
}
}
int ans = 1;
for (int i = 1; i <= n; i++)
if (par[i] < 0)
ans = ans * 2 % mod;
cout << ans;
return 0;
}
