#include <bits/stdc++.h>
#define FOR(x, a, b) for (int x = a; x <= b; ++x)
#define FOD(x, a, b) for (int x = a; x >= b; --x)
#define REP(x, a, b) for (int x = a; x < b; ++x)
#define DEBUG(X) { cout << #X << " = " << X << endl; }
#define PR(A, n) { cout << #A << " = "; FOR(_, 1, n) cout << A[_] << " "; cout << endl; }
#define PR0(A, n) { cout << #A << " = "; REP(_, 0, n) cout << A[_] << " "; cout << endl; }
#define BitCount(x) __builtin_popcount(x)
using namespace std;
typedef pair <int, int> II;
typedef long long LL;
const int N = 2 * (1e6 + 10);
const int INF = 0x3f3f3f3f;
const int BASE = 1e9 + 7;
int n;
int a[N], b[N], c[N], pos[N];
struct Segment {
int l, r;
Segment () {}
Segment (int l, int r) : l(l), r(r) {}
bool operator < (const Segment &that) const {
return l < that.l;
}
} seg[N];
struct SegmentTree {
#define m ((l + r) >> 1)
int st[2][4 * N];
void Build(int k, int l, int r) {
if (l == r) {
st[0][k] = (a[l] > l ? a[l] : 0);
st[1][k] = (a[l] < l ? a[l] : INF);
return;
}
Build(k << 1, l, m);
Build(k << 1 | 1, m + 1, r);
st[0][k] = max(st[0][k << 1], st[0][k << 1 | 1]);
st[1][k] = min(st[1][k << 1], st[1][k << 1 | 1]);
}
void Push1(int k, int l, int r, int i, int j, int val, int u, queue <int> &Q) {
if (l > j || r < i) return;
if (st[0][k] < val) return;
if (l == r) {
st[0][k] = 0;
int v = pos[l];
if (v == u) return;
if (c[v] == -1) {
c[v] = c[u] ^ 1;
Q.push(v);
}
return;
}
Push1(k << 1, l, m, i, j, val, u, Q);
Push1(k << 1 | 1, m + 1, r, i, j, val, u, Q);
st[0][k] = max(st[0][k << 1], st[0][k << 1 | 1]);
}
void Push2(int k, int l, int r, int i, int j, int val, int u, queue <int> &Q) {
if (l > j || r < i) return;
if (st[1][k] > val) return;
if (l == r) {
st[1][k] = INF;
int v = pos[l];
if (v == u) return;
if (c[v] == -1) {
c[v] = c[u] ^ 1;
Q.push(v);
}
return;
}
Push2(k << 1, l, m, i, j, val, u, Q);
Push2(k << 1 | 1, m + 1, r, i, j, val, u, Q);
st[1][k] = min(st[1][k << 1], st[1][k << 1 | 1]);
}
void Disable(int k, int l, int r, int i) {
if (l == r) {
st[0][k] = 0;
st[1][k] = INF;
return;
}
if (i <= m) Disable(k << 1, l, m, i);
else Disable(k << 1 | 1, m + 1, r, i);
st[0][k] = max(st[0][k << 1], st[0][k << 1 | 1]);
st[1][k] = min(st[1][k << 1], st[1][k << 1 | 1]);
}
#undef m
} ST;
bool Check(vector <Segment> &A) {
sort(A.begin(), A.end());
memset(b, -1, sizeof b);
REP(i, 0, A.size()) {
b[A[i].l] = A[i].r;
b[A[i].r] = A[i].l;
}
stack <int> ST;
FOR(timer, 1, 2 * n) {
if (b[timer] == -1) continue;
if (b[timer] > timer) {
int l = timer, r = b[timer];
if (ST.size() == 0 || ST.top() > r) ST.push(r);
else return false;
} else {
int r = timer;
if (ST.size() && ST.top() == r) ST.pop();
else return false;
}
}
return true;
}
int main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif // LOCAL
scanf("%d", &n);
FOR(i, 1, n) {
int l, r; scanf("%d%d", &l, &r);
seg[i] = Segment(l, r);
}
sort(seg + 1, seg + n + 1);
memset(c, -1, sizeof c);
FOR(i, 1, n) {
int l = seg[i].l, r = seg[i].r;
pos[l] = i; pos[r] = i;
a[l] = r; a[r] = l;
}
ST.Build(1, 1, 2 * n);
LL ans = 1;
FOR(i, 1, n) if (c[i] == -1) {
// DEBUG(i);
queue <int> Q; Q.push(i);
ST.Disable(1, 1, 2 * n, seg[i].l);
ST.Disable(1, 1, 2 * n, seg[i].r);
c[i] = 0;
while (Q.size()) {
int u = Q.front(); Q.pop();
int l = seg[u].l, r = seg[u].r;
//cout << u << " = " << l << " " << r << endl;
ST.Push1(1, 1, 2 * n, l, r, r, u, Q);
ST.Push2(1, 1, 2 * n, l, r, l, u, Q);
}
ans = ans * 2 % BASE;
}
vector <Segment> Z[2];
FOR(i, 1, n) Z[c[i]].push_back(seg[i]);
FOR(i, 0, 1) if (Check(Z[i]) == false) {
puts("0");
return 0;
}
cout << ans;
return 0;
}
