#include <bits/stdc++.h>
using namespace std;
#define cerr cerr << "DEBUG "
constexpr int N = 2e6 + 10;
struct SegTree {
int t[N << 2], zz;
bool minmode;
SegTree(bool mm) : minmode(mm) {
zz = mm ? N : -1;
fill(t, t + (N << 2), zz);
}
int pull(int l, int r) {
if (minmode) {
return min(l, r);
}
return max(l, r);
}
void update(int c, int b, int e, int i, int x) {
if (e - b == 1) {
t[c] = x;
return;
}
int m = (b + e) >> 1, l = c << 1, r = l | 1;
if (i < m) {
update(l, b, m, i, x);
} else {
update(r, m, e, i, x);
}
t[c] = pull(t[l], t[r]);
}
int query(int c, int b, int e, int u, int v) {
if (e <= u || v <= b) {
return zz;
}
if (u <= b && e <= v) {
return t[c];
}
int m = (b + e) >> 1, l = c << 1, r = l | 1;
return pull(query(l, b, m, u, v), query(r, m, e, u, v));
}
};
int n, ind[N], l[N], r[N];
bool isl[N];
SegTree segmn(true), segmx(false);
vector<int> vec[2];
bool color[N];
bool mark[N];
void dfs(int v) {
mark[v] = true;
segmn.update(1, 0, n << 1, r[v], segmn.zz);
segmx.update(1, 0, n << 1, l[v], segmx.zz);
vec[color[v]].push_back(l[v]);
vec[color[v]].push_back(r[v]);
int ret = segmn.query(1, 0, n << 1, l[v] + 1, r[v]);
while (ret < l[v]) {
color[ind[ret]] = color[v] ^ 1;
dfs(ind[ret]);
ret = segmn.query(1, 0, n << 1, l[v] + 1, r[v]);
}
ret = segmx.query(1, 0, n << 1, l[v] + 1, r[v]);
while (ret > r[v]) {
color[ind[ret]] = color[v] ^ 1;
dfs(ind[ret]);
ret = segmx.query(1, 0, n << 1, l[v] + 1, r[v]);
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for (int i = 0; i < n; ++i) {
cin >> l[i] >> r[i];
--l[i], --r[i];
ind[l[i]] = ind[r[i]] = i;
isl[l[i]] = true;
segmn.update(1, 0, n << 1, r[i], l[i]);
segmx.update(1, 0, n << 1, l[i], r[i]);
}
int cnt = 0;
for (int i = 0; i < n; ++i) {
if (!mark[i]) {
++cnt;
for (int j = 0; j < 2; ++j) {
vec[j].clear();
}
dfs(i);
for (int j = 0; j < 2; ++j) {
sort(vec[j].begin(), vec[j].end());
vector<int> stk;
for (auto &x : vec[j]) {
if (isl[x]) {
stk.push_back(x);
} else {
if (stk.back() != l[ind[x]]) {
cout << 0;
exit(0);
}
stk.pop_back();
}
}
}
}
}
int res = 1;
while (cnt--) {
res <<= 1;
if (res >= 1000000007) {
res -= 1000000007;
}
}
cout << res;
}
