#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int mod = 1e9 + 7;
#define F first
#define S second
const int N = 2e6 + 20, inf = 3e7;
pair<int, int> a[N], b[N], seg[N << 2][2];
int n;
bool visited[N];
int col[N];
stack<int> st;
void build(int u = 1, int s = 0, int e = N)
{
seg[u][0] = {inf, s}; seg[u][1] = {-inf, s};
if (e - s < 2) return;
int lc = u << 1, rc = lc | 1, mid = (s + e) >> 1;
build(lc, s, mid); build(rc, mid, e);
return;
}
void add(int ind, int ff, int x, int u = 1, int s = 0, int e = 2 * n)
{
if (e - s < 2)
{
seg[u][ff] = {x, s};
return;
}
int lc = u << 1, rc = lc | 1, mid = (s + e) >> 1;
if (ind < mid)
add(ind, ff, x, lc, s, mid);
else
add(ind, ff, x, rc, mid, e);
if (ff == 0) seg[u][ff] = min(seg[lc][ff], seg[rc][ff]);
else seg[u][ff] = max(seg[lc][ff], seg[rc][ff]);
return;
}
pair<int, int> get(int l, int r, int ff, int u = 1, int s = 0, int e = 2 * n)
{
if (e <= l || r <= s)
{
if (ff == 0) return {inf, s};
return {-inf, s};
}
if (l <= s && r >= e) return seg[u][ff];
int lc = u << 1, rc = lc | 1, mid = (s + e) >> 1;
if (ff == 0) return min(get(l, r, ff, lc, s, mid), get(l, r, ff, rc, mid, e));
return max(get(l, r, ff, lc, s, mid), get(l, r, ff, rc, mid, e));
}
void dfs(int u)
{
visited[u] = true;
int l = a[u].F, r = a[u].S;
add(r, 0, inf); add(l, 1, -inf);
if (r - l >= 2)
{
while (true)
{
pair<int, int> pp = get(l + 1, r, 0);
if (pp.F >= l) break;
int ind = b[pp.S].F;
if (!visited[ind])
{
col[ind] = 1 - col[u];
dfs(ind);
}
}
while (true)
{
pair<int, int> pp = get(l + 1, r, 1);
if (pp.F <= r) break;
int ind = b[pp.S].F;
if (!visited[ind])
{
col[ind] = 1 - col[u];
dfs(ind);
}
}
}
return;
}
inline bool check(int ff)
{
while (!st.empty()) st.pop();
for (int i = 0; i < 2 * n; i++)
{
if (col[b[i].F] != ff) continue;
int x = b[i].F;
if (b[i].S == 0)
{
st.push(x);
continue;
}
if (st.top() != x) return false;
st.pop();
}
return true;
}
int main()
{
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
build();
cin >> n;
for (int i = 0; i < n; i++)
{
int l, r;
cin >> l >> r;
l--; r--;
a[i] = {l, r};
b[l] = {i, 0}; b[r] = {i, 1};
add(r, 0, l);
add(l, 1, r);
}
int tt = 0;
for (int i = 0; i < n; i++)
{
if (!visited[i])
{
dfs(i);
tt++;
}
}
if ((!check(0)) || (!check(1))) cout << 0;
else
{
int ans = 1;
for (int i = 0; i < tt; i++) ans = 1ll * ans * 2 % mod;
cout << ans;
}
return 0;
}
