#include<bits/stdc++.h>
using namespace std;
using pii = pair<int,int>;
#define ff first
#define ss second
#define pb push_back
#define all(a) (a).begin(), (a).end()
constexpr int maxn = 2e6+10, inf = 0x3f3f3f3f, mod = 1000000007;
struct SegmentTree
{
int base[maxn], tree[4*maxn], k;
SegmentTree(int _k) : k(_k) {}
inline int op(int a, int b) {return k?max(a,b):min(a,b);}
void build(int node, int i, int j) {
if(i == j) return (void)(tree[node] = base[i]?base[i]:(k?-inf:inf));
int m = (i+j) >> 1;
build(2*node, i, m); build(2*node+1, m+1, j);
tree[node] = op(tree[2*node], tree[2*node+1]);
}
void rm(int node, int i, int j, int pos) {
if(i == j) return (void)(tree[node] = k?-inf:inf);
int m = (i+j) >> 1;
if(pos <= m) rm(2*node, i, m, pos);
else rm(2*node+1, m+1, j, pos);
tree[node] = op(tree[2*node], tree[2*node+1]);
}
int query(int node, int i, int j, int l, int r, int val) {
if(i > r || j < l) return k?-inf:inf;
if(i >= l && j <= r) return tree[node];
int m = (i+j) >> 1;
return op(query(2*node, i, m, l, r, val), query(2*node+1, m+1, j, l, r, val));
}
} seg0(0), seg1(1);
pii a[maxn];
int pos[2*maxn], cor[maxn], mark[maxn], n;
void dfs(int i, int C) {
cor[i] = C;
mark[i] = 1;
seg0.rm(1, 1, 2*n, a[i].ss);
seg1.rm(1, 1, 2*n, a[i].ff);
int next;
while((next = seg1.query(1, 1, 2*n, a[i].ff+1, a[i].ss, a[i].ss)) > a[i].ss)
dfs(pos[next], !C);
while((next = seg0.query(1, 1, 2*n, a[i].ff, a[i].ss-1, a[i].ff)) < a[i].ff)
dfs(pos[next], !C);
}
int power(int b, int e) {
int ans = 1;
while(e) {
if(e&1) ans = (int)(1ll * ans * b % mod);
b = (int)(1ll * b * b % mod);
e >>= 1;
}
return ans;
}
int main() {
scanf("%d", &n);
for(int i = 1; i <= n; i++) {
scanf("%d %d", &a[i].ff, &a[i].ss);
pos[a[i].ff] = i, pos[a[i].ss] = i;
seg1.base[a[i].ff] = a[i].ss, seg0.base[a[i].ss] = a[i].ff;
}
seg0.build(1, 1, 2*n);
seg1.build(1, 1, 2*n);
int cc = 0;
for(int i = 1; i <= n; i++)
if(!mark[i]) ++cc, dfs(i, 0);
vector<int> b, w, st;
for(int i = 1; i <= n; i++)
if(cor[i])
w.pb(a[i].ff), w.pb(a[i].ss);
else b.pb(a[i].ff), b.pb(a[i].ss);
sort(all(w)), sort(all(b));
int ok = 1;
for(int x : w)
if(st.size() && st.back() == pos[x])
st.pop_back();
else st.pb(pos[x]);
if(st.size()) ok = 0;
st.clear();
for(int x : b)
if(st.size() && st.back() == pos[x])
st.pop_back();
else st.pb(pos[x]);
if(st.size()) ok = 0;
printf("%d\n", ok?power(2, cc):0);
}
