#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
#define x first
#define y second
#define all(x) x.begin(), x.end()
const int N = 1<<20;
const int MOD = 1e9+7;
int n;
pii A[N];
pii ev[N<<1], ev2[N<<1];
int col[N];
vector<pii> seg[N<<2], seg2[N<<2];
int ptr[N<<2], ptr2[N<<2];
void build(vector<pii> seg[], int ptr[], pii ev[], int p=1, int b=0, int e=2*n-1)
{
if (b == e) {
if (ev[b].y == 1)
seg[p].push_back(pii(A[ev[b].x].y, ev[b].x));
} else {
int m = (b+e)/2;
build(seg, ptr, ev, p<<1, b, m);
build(seg, ptr, ev, p<<1|1, m+1, e);
merge(all(seg[p<<1]), all(seg[p<<1|1]), back_inserter(seg[p]));
}
ptr[p] = seg[p].size()-1;
//printf("node %d [%d,%d]:", p, b, e);
//for (auto x : seg[p]) printf(" %d", x);
//printf("\n");
}
pii amort(vector<pii> seg[], int ptr[], int p, int b, int e)
{
//printf("amortizing %d %d %d\n", p, b, e);
while (ptr[p] >= 0 && col[seg[p][ptr[p]].y])
--ptr[p];
return ptr[p] == -1 ? pii(-1, -1) : seg[p][ptr[p]];
}
pii get(vector<pii> seg[], int ptr[], int l, int r, int p=1, int b=0, int e=2*n-1)
{
if (b > r || e < l)
return pii(-1, -1);
if (b >= l && e <= r)
return amort(seg, ptr, p, b, e);
int m = (b+e)/2;
return max(get(seg, ptr, l, r, p<<1, b, m), get(seg, ptr, l, r, p<<1|1, m+1, e));
}
inline bool intersect(int al, int ar, int bl, int br)
{
if (bl > ar || br < al) return false;
if (bl >= al && br <= ar) return false;
if (al >= bl && ar <= br) return false;
return true;
}
void solve(int i)
{
//printf("solve %d, color = %d\n", i, col[i]);
bool att = true;
while (true) {
pii ans(-1, -1);
if (att)
ans = get(seg, ptr, A[i].x, A[i].y);
if (ans == pii(-1, -1)) {
att = false;
ans = get(seg2, ptr2, 2*n-A[i].y-1, 2*n-A[i].x-1);
}
int j = ans.y;
if (ans == pii(-1, -1) || !intersect(A[i].x, A[i].y, A[j].x, A[j].y))
break;
col[j] = col[i] == 1 ? 2 : 1;
solve(j);
}
}
int main()
{
scanf("%d", &n);
for (int i = 0; i < n; ++i) {
scanf("%d%d", &A[i].x, &A[i].y);
ev[--A[i].x] = pii(i, 1);
ev[--A[i].y] = pii(i, 2);
//printf("%d: %d %d\n", i, A[i].x, A[i].y);
int fx = 2*n-A[i].x-1, fy = 2*n-A[i].y-1;
ev2[fy] = pii(i, 1);
ev2[fx] = pii(i, 2);
//printf("%d': %d %d\n", i, fy, fx);
}
build(seg, ptr, ev);
build(seg2, ptr2, ev2);
int ans = 1;
for (int i = 0; i < n; ++i) {
if (!col[i]) {
col[i] = 1;
solve(i);
ans = (ans*2)%MOD;
}
}
stack<int> S[2];
for (int i = 0; i < 2*n; ++i) {
int x = ev[i].x, t = ev[i].y;
int c = col[x]-1;
if (t == 1)
S[c].push(x);
else {
if (S[c].top() != x) {
ans = 0;
break;
}
S[c].pop();
}
}
printf("%d\n", ans);
return 0;
}
