#include<iostream>
#include<vector>
#include<algorithm>
#include<set>
using namespace std;
#define ll long long
#define ld long double
#define pii pair<int, int>
#define pli pair<ll, ll>
#define ppi pair<pii, pii>
#define RUN_LIKE_DJAWAD (ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0));
#define DECIMAL_OUTPUT cout << fixed << setprecision(9);
#define pb push_back
#define pf push_top
#define ff first
#define ss second
#define maxn 2000001
int seg[maxn << 2];
vector<int> now;
set<int> av[maxn];
int col[maxn];
int st[maxn], fn[maxn];
int sz[maxn], par[maxn];
vector<int> g[maxn];
int n;
void upd(int l, int r, int p, int x, int id){
if (l == r){
seg[id] = x;
return;
}
int mid = (l + r) >> 1;
if (p <= mid) upd(l, mid, p, x, id << 1);
else upd(mid + 1, r, p, x, (id << 1) + 1);
seg[id] = seg[id << 1] + seg[(id << 1) + 1];
}
int get(int v){
while (par[v] != -1) v = par[v];
return v;
}
void merge(int u, int v){
int pu = get(u), pv = get(v);
if (pu != pv){
g[u].pb(v);
g[v].pb(u);
if (sz[pu] < sz[pv]) swap(pu, pv);
if (not av[pu].empty()) upd(1, n << 1, *av[pu].begin(), 0, 1);
if (not av[pv].empty()) upd(1, n << 1, *av[pv].begin(), 0, 1);
for (int p: av[pv]) av[pu].insert(p);
av[pv].clear();
if (not av[pu].empty()) upd(1, n << 1, *av[pu].begin(), 1, 1);
par[pv] = pu;
sz[pu] += sz[pv];
}
}
void gbv(int l, int r, int s, int e, int id){
if (seg[id] == 0 or s > r or e < l) return;
if (l == r){
now.pb(col[l]);
return;
}
int mid = (l + r) >> 1;
gbv(l, mid, s, e, id << 1);
gbv(mid + 1, r, s, e, (id << 1) + 1);
}
bool seen[maxn];
int cl[maxn];
void dfs(int v, int nc){
seen[v] = true;
cl[v] = nc;
for (int u: g[v]) if (not seen[u]) dfs(u, nc ^ 1);
}
int gs(int l, int r, int s, int e, int id){
if (s > r or e < l) return 0;
if (s <= l and e >= r) return seg[id];
int mid = (l + r) >> 1;
return gs(l, mid, s, e, id << 1) + gs(mid + 1, r, s, e, (id << 1) + 1);
}
const int mod = 1e9 + 7;
int main(){
RUN_LIKE_DJAWAD
cin >> n;
for (int i = 1; i <= n; i++){
cin >> st[i] >> fn[i];
col[st[i]] = i, col[fn[i]] = i;
}
for (int i = 1; i <= n; i++) par[i] = -1, sz[i] = 1;
for (int i = 1; i <= n << 1; i++){
int c = col[i];
int s = st[c], e = fn[c];
int ncc = get(c);
if (not av[ncc].empty()) upd(1, n << 1, *av[ncc].begin(), 0, 1);
if (s == i){
av[ncc].insert(e);
upd(1, n << 1, *av[ncc].begin(), 1, 1);
gbv(1, n << 1, s + 1, e - 1, 1);
for (int u: now) merge(c, u);
now.clear();
} else {
av[ncc].erase(e);
if (not av[ncc].empty()) upd(1, n << 1, *av[ncc].begin(), 1, 1);
}
}
int ans = 1;
for (int i = 1; i <= n; i++) if (not seen[i]){
ans = (ans << 1) % mod;
dfs(i, 1);
}
for (int i = 1; i < maxn << 2; i++) seg[i] = 0;
for (int i = 1; i <= n << 1; i++){
int c = col[i];
int s = st[c], e = fn[c];
if (s == i){
if (cl[c] == 0){
upd(1, n << 1, e, 1, 1);
if (gs(1, n << 1, s + 1, e - 1, 1) > 0) ans = 0;
}
} else {
if (cl[c] == 0) upd(1, n << 1, e, 0, 1);
}
}
for (int i = 1; i < maxn << 2; i++) seg[i] = 0;
for (int i = 1; i <= n << 1; i++){
int c = col[i];
int s = st[c], e = fn[c];
if (s == i){
if (cl[c] == 1){
upd(1, n << 1, e, 1, 1);
if (gs(1, n << 1, s + 1, e - 1, 1) > 0) ans = 0;
}
} else {
if (cl[c] == 1) upd(1, n << 1, e, 0, 1);
}
}
// for (int i = 1; i <= n; i++) cout << cl[i] << " ";
// cout << "\n";
cout << ans << "\n";
}
