#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pf push_front
#define iter(v, i) for (__typeof__((v).begin()) i = (v).begin(); i != (v).end(); i++)
#define fast_io_without_cstdio ios_base::sync_with_stdio(false), cin.tie(NULL)
#define all(v) (v).begin(), (v).end()
#define rep(i, s, e) for (int i = s; i < e; i++)
// START for segment tree
#define params int p, int L, int R
#define housekeep int mid = (L + R) >> 1, left = p << 1, right = left | 1
// END
#ifdef __linux__
#define gc getchar_unlocked
#define pc putchar_unlocked
#else
#define gc getchar
#define pc putchar
#endif
#if __cplusplus <= 199711L
template<class BidirIt>
BidirIt prev(BidirIt it, typename iterator_traits<BidirIt>::difference_type n = 1) {
advance(it, -n);
return it;
}
template<class ForwardIt>
ForwardIt next(ForwardIt it, typename iterator_traits<ForwardIt>::difference_type n = 1) {
advance(it, n);
return it;
}
#endif
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef long double ldouble;
const double EPS = 1e-9;
const double PI = 3.141592653589793238462;
template<typename T>
inline T sq(T a) { return a * a; }
//#ifdef LOCAL_MACHINE
//#endif
const int MAXN = 1e6 + 5;
const int MOD = 1e9 + 7;
#define BLUE 0
#define RED 1
int sz;
void upd(int *st, int p, int val) {
st[p] = max(st[p], val);
return;
// END
p += sz;
st[p] = max(st[p], val);
for (; p > 1; p >>= 1) {
st[p >> 1] = max(st[p], st[p ^ 1]);
}
}
int query(int *st, int l, int r) {
int ans = 0;
for (int i = l; i <= r; i++)
ans = max(ans, st[i]);
return ans;
// END
int res = 0;
l += sz, r += sz;
for (; l <= r; l >>= 1, r >>= 1) {
if (l & 1) res = max(res, st[l++]);
if (!(r & 1)) res = max(res, st[r--]);
}
return res;
}
ii seg[MAXN];
int col[MAXN], who[MAXN * 2];
int st[2][MAXN << 2];
bool exist[MAXN];
vi ds[MAXN << 2];
void ins(params, int i, int j, int val) {
if (i > R || j < L) return;
if (i <= L && j >= R) {
ds[p].pb(val);
return;
}
housekeep;
ins(left, L, mid, i, j, val);
ins(right, mid + 1, R, i, j, val);
}
void rec(params, int x, vi &vec) {
for (int i = 1; i <= sz / 2; i++)
if (exist[i] && seg[i].fi < x && seg[i].se > x) {
vec.pb(i);
exist[i] = false;
}
return;
// END
for (auto it : ds[p]) {
if (exist[it]) vec.pb(it);
exist[it] = false;
}
ds[p].clear();
if (L == R) return;
housekeep;
if (x <= mid)
rec(left, L, mid, x, vec);
else
rec(right, mid + 1, R, x, vec);
}
int main() {
//freopen("", "r", stdin);
//freopen("", "w", stdout);
int n;
scanf("%d", &n);
sz = 2 * n;
for (int i = 1; i <= n; i++) {
scanf("%d %d", &seg[i].fi, &seg[i].se);
seg[i].fi--;
seg[i].se--;
}
memset(col, -1, sizeof col);
sort(seg + 1, seg + n + 1);
for (int i = 1; i <= n; i++) {
who[seg[i].fi] = who[seg[i].se] = i;
exist[i] = true;
ins(1, 0, sz - 1, seg[i].fi, seg[i].se, i);
}
int ans = 1;
for (int i = 1; i <= n; i++) {
exist[i] = false;
if (col[i] == -1) {
if (query(st[RED], seg[i].fi, seg[i].se) > seg[i].se) {
col[i] = BLUE;
} else {
if (query(st[BLUE], seg[i].fi, seg[i].se) <= seg[i].se) {
ans *= 2;
while (ans >= MOD) ans -= MOD;
}
col[i] = RED;
}
}
/*
while (proc <= n && seg[proc].fi <= seg[i].fi)
proc++;
while (proc <= n && seg[proc].fi <= seg[i].se) {
active.insert(seg[proc].se);
proc++;
}
if (active.count(seg[i].se)) active.erase(seg[i].se);
*/
if (query(st[col[i]], seg[i].fi, seg[i].se) > seg[i].se) {
ans = 0;
break;
}
vi vec;
rec(1, 0, sz - 1, seg[i].se, vec);
for (auto it : vec) {
col[it] = 1 - col[i];
upd(st[col[it]], seg[it].fi, seg[it].se);
}
/*
if (active.empty()) continue;
for (auto it = prev(active.end()); *it > seg[i].se; it = prev(it)) {
upd(st[1 - col[i]], seg[who[*it]].fi, *it);
col[who[*it]] = 1 - col[i];
it = active.erase(it);
if (active.empty()) break;
}
*/
}
printf("%d\n", ans);
return 0;
}
