#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e6+10;
const int inf = 1e9+10;
const int mod = 1e9+7;
int n;
int l[maxn], r[maxn];
int cor[maxn], comp[maxn];
int back[maxn];
int tree[2][4*maxn];
vector<int> one, zero;
void build(int node, int l, int r)
{
if (l == r)
{
tree[0][node] = inf;
tree[1][node] = -inf;
return;
}
int mid = (l+r)>>1;
build(2*node, l, mid); build(2*node+1, mid+1, r);
tree[0][node] = min(tree[0][2*node], tree[0][2*node+1]);
tree[1][node] = max(tree[1][2*node], tree[1][2*node+1]);
}
void upd(int node, int l, int r, int pos, int v, int k)
{
if (l == r)
{
tree[k][node] = v;
return;
}
int mid = (l+r)>>1;
if (pos <= mid) upd(2*node, l, mid, pos, v, k);
else upd(2*node+1, mid+1, r, pos, v, k);
tree[0][node] = min(tree[0][2*node], tree[0][2*node+1]);
tree[1][node] = max(tree[1][2*node], tree[1][2*node+1]);
}
int query(int node, int l, int r, int a, int b, int k)
{
if (l > b || r < a) return (k == 0 ? inf : -inf);
if (l >= a && r <= b) return tree[k][node];
int mid = (l+r)>>1;
int p1 = query(2*node, l, mid, a, b, k), p2 = query(2*node+1, mid+1, r, a, b, k);
if (!k) return min(p1, p2);
return max(p1, p2);
}
void dfs(int u, int C, int cc)
{
comp[u] = cc, cor[u] = C;
while (true)
{
int x = query(1, 1, 2*n, l[u]+1, r[u]-1, 0);
if (x >= l[u]) break;
upd(1, 1, 2*n, r[back[x]], inf, 0);
upd(1, 1, 2*n, l[back[x]], -inf, 1);
dfs(back[x], (!C ? 1 : 0), cc);
}
while (true)
{
int x = query(1, 1, 2*n, l[u]+1, r[u]-1, 1);
if (x <= r[u]) break;
upd(1, 1, 2*n, r[back[x]], inf, 0);
upd(1, 1, 2*n, l[back[x]], -inf, 1);
dfs(back[x], (!C ? 1 : 0), cc);
}
}
bool cmp(int a, int b)
{
return l[a] < l[b];
}
bool ok(bool k)
{
stack<int> stk;
if (!k)
{
for (auto i: zero)
{
while (stk.size() && l[i] > stk.top())
stk.pop();
if (stk.size() && stk.top() > l[i] && stk.top() < r[i])
return 0;
stk.push(r[i]);
}
}
else
{
for (auto i: one)
{
while (stk.size() && l[i] > stk.top())
stk.pop();
if (stk.size() && stk.top() > l[i] && stk.top() < r[i])
return 0;
stk.push(r[i]);
}
}
return 1;
}
int main(void)
{
scanf("%d", &n);
build(1, 1, 2*n);
for (int i = 1; i <= n; i++)
{
scanf("%d %d", &l[i], &r[i]);
back[l[i]] = back[r[i]] = i;
upd(1, 1, 2*n, r[i], l[i], 0);
upd(1, 1, 2*n, l[i], r[i], 1);
}
int cc = 0;
for (int i = 1; i <= n; i++)
{
if (!comp[i])
{
upd(1, 1, 2*n, r[i], inf, 0);
upd(1, 1, 2*n, l[i], -inf, 1);
dfs(i, 0, ++cc);
}
}
for (int i = 1; i <= n; i++)
{
if (cor[i] == 0) zero.push_back(i);
else one.push_back(i);
}
sort(zero.begin(), zero.end(), cmp);
sort(one.begin(), one.end(), cmp);
if (!ok(0) || !ok(1))
{
printf("0\n");
return 0;
}
int ans = 1;
for (int i = 1; i <= cc; i++)
ans = (ans*2)%mod;
printf("%d\n", ans);
}
