#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using vi = vector<int>;
using vll = vector<ll>;
using vii = vector<ii>;
const ll MOD = 1e9+7;
const int INF = 1e9+9;
const int MAXN = 1000006;
template <class T, class Operations>
struct LzySegTree {
int n, h; // Size and height of the array
vector<T> st; // Segment tree (size 2n)
Operations op; // Update operation object
void build(int L, int R) {
int len = 2;
for (L += n, R += n - 1; L > 1; len <<= 1) {
L >>= 1, R >>= 1;
for (int i = R; i >= L; --i) op.calc(i, len);
}
}
/**
* @brief Recalculate the values of all parents of node p, taking into
* account delayed operations.
*/
void build(int p) {
// Find value from children, apply every delayed operation you have for
// this node
int len = 2;
for (p+=n; p > 1; len <<= 1) p >>= 1, op.calc(p, len);
}
void push(int L, int R) {
int s = h, len = 1 << h;
for (L += n, R += n - 1; s > 0; --s, len >>= 1)
for (int i = L >> s; i <= R >> s; ++i) op.pushDelOps(i, len);
}
/**
* @brief Propagate changes from all parents of node p
*/
void push(int p) {
for (int s = h, len = 1 << h; s > 0; --s, len >>= 1)
op.pushDelOps(p >> s, len);
}
/**
* @brief Perform update operation on the interval [L, R)
* @param value
*/
void update(int L, int R, typename Operations::UpdateObject value) {
if (L < n) push(L, L + 1);
if (R > 0) push(R - 1, R);
int L0 = L, R0 = R, len = 1;
for (L += n, R += n; L < R; L >>= 1, R >>= 1, len <<= 1) {
if (L & 1) op.updateOp(L++, len, value);
if (R & 1) op.updateOp(--R, len, value);
}
build(L0, L0 + 1), build(R0 - 1, R0);
}
/**
* @brief Query on the interval [L, R)
*/
T query(int L, int R) {
if (L < n) push(L, L + 1);
if (R > 0) push(R - 1, R);
/*for (int i = 1; i < 2 * n; i++) {
cout << i << ": " << st[i] << " ";
if (i < n) cout << op.d[i];
cout << endl;
}*/
T resl = op.identity, resr = op.identity;
for (L += n, R += n; L < R; L >>= 1, R >>= 1) {
if (L & 1) resl = op.op(resl, st[L++]);
if (R & 1) resr = op.op(st[--R], resr);
}
return op.op(resl, resr);
}
/**
* @brief Construct a new Segment Tree object.
*
* @param A Array of elements
*/
LzySegTree(const vector<T> &A)
: n((int)A.size()),
h(sizeof(int) * 8 - __builtin_clz(n)),
st(n << 1),
op(*this) {
copy(A.begin(), A.end(), st.begin() + n);
build(0, n);
}
};
template<typename T>
struct SetForMinMax {
const T identity = -INF;
using UpdateObject = T;
LzySegTree<int, SetForMinMax> &st; vector<int> d;
SetForMinMax(LzySegTree<int, SetForMinMax> &st) : st(st), d(st.n, INF) {}
static inline int op(int a, int b) {
return max(a, b);
}
inline void calc(int p, int len) {
st.st[p] = d[p] == INF? max(st.st[p<<1], st.st[p<<1|1]) : d[p];
}
inline void updateOp(int p, int len, int value) {
st.st[p] = value;
if (p < st.n) d[p] = value;
}
inline void pushDelOps(int p, int len) {
if (d[p] != INF) {
updateOp(p<<1, len>>1, d[p]);
updateOp(p<<1|1, len>>1, d[p]);
d[p] = INF;
}
}
};
using ST = LzySegTree<int, SetForMinMax<int>>;
int n, a[MAXN], b[MAXN], e[MAXN], ind[MAXN], col[MAXN];
void dfs(ST& segl, ST& segr, int u, int c) {
segl.update(b[u], b[u]+1, -INF);
segr.update(a[u], a[u]+1, -INF);
col[u] = c;
int l, r;
while (r = segr.query(a[u]+1, b[u]), r != -INF and r > b[u]) {
dfs(segl, segr, ind[r], 3-c);
}
while (l = -segl.query(a[u]+1, b[u]), l != INF and l < a[u]) {
dfs(segl, segr, ind[l], 3-c);
}
}
int main () {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
ST segl(vi(2*n, -INF));
ST segr(vi(2*n, -INF));
for (int i = 1; i <= n; ++i) {
cin >> a[i] >> b[i]; --a[i], --b[i];
ind[b[i]] = ind[a[i]] = i;
segl.update(b[i], b[i]+1, -a[i]);
segr.update(a[i], a[i]+1, b[i]);
}
ll ans = 1;
for (int i = 1; i <= n; ++i) {
if (!col[i]) {
ans *= 2;
if (ans >= MOD) ans -= MOD;
dfs(segl, segr, i, 1);
}
}
vi st[2];
for (int i = 0; i < 2*n; ++i) {
int v = ind[i], c = col[v]-1;
if (i == a[v]) {
st[c].push_back(v);
} else {
if (!st[c].empty() and st[c].back() == v) {
st[c].pop_back();
} else {
ans = 0;
}
}
}
cout << ans << endl;
}
