#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 Oper>
struct LzySegTree {
int n, h; vector<T> st;
Oper op;
LzySegTree() : op((this)) { }
LzySegTree(const vector<T> &A)
: n(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);
}
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);
}
}
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);
}
void update(int L, int R, typename Oper::TUpd val) {
push(L, L+1), 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, val);
if (R&1) op.updateOp(--R, len, val);
}
build(L0, L0+1), build(R0-1, R0);
}
T query(int L, int R) {
push(L, L+1), push(R-1, R);
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);
}
void print() {
for (int i = 0; i < n; ++i) {
cerr << i << ": " << st[i] << " d(" << op.d[i] << endl;
}
for (int i = n; i < 2*n; ++i) {
cerr << i << ": " << st[i] << endl;
}
}
};
template<typename T>
struct SetForMinMax {
const T identity = -INF;
using TUpd = 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) {
if (value == INF) return;
st.st[p] = value;
if (p < st.n) d[p] = value;
}
inline void pushDelOps(int p, int len) {
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) {
segr.update(a[u], a[u]+1, -INF);
segl.update(b[u], b[u]+1, -INF);
col[u] = c;
int l, r;
while (r = segr.query(a[u]+1, b[u]), 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;
LzySegTree<int, SetForMinMax<int>> segl(vi(2*n, -INF));
LzySegTree<int, SetForMinMax<int>> 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;
}
