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#include <bits/stdc++.h>
using namespace std;

#define fwd(i, a, n) for (int i = (a); i < (n); i ++)
#define rep(i, n) fwd(i, 0, n)
#define all(X) begin(X), end(X)
#define sz(X) ((int)X.size())
#define st first
#define nd second
#define pii pair<int, int>
#define vi vector<int>
#define ll long long

#ifdef LOC
auto &operator << (auto &out, pair<auto, auto> a) {
	return out << "(" << a.st << ", " << a.nd << ")";
}

auto &operator << (auto &out, auto a) {
	out << "{";
	for (auto b : a)
		out << b << ", ";
	return out << "}";
}

void dump(auto... x) { ((cerr << x << ", "), ...) << '\n'; }

#define debug(x...) cerr << "[" #x "]: ", dump(x)
#else
#define debug(...) 0
#endif

const int part_base = (1 << 19);
const int maxN = 500 * 1000 + 10;
const int mod = 1e9 + 7;

int inv(int k) {
	int w = mod - 2;
	int r = 1;
	while (w) {
		if (w & 1)
			r = 1ll * r * k % mod;
		k = 1ll * k * k % mod;
		w /= 2;
	}
	return r;
}

int inwers[maxN];

void prep_inwers() {
	inwers[0] = 1;
	fwd(i, 1, maxN)
		inwers[i] = 1ll * inwers[i - 1] * i % mod;
	int ifact = inv(inwers[maxN - 1]);
	for (int i = maxN - 1; i >= 1; i --) {
		inwers[i] = 1ll * ifact * inwers[i - 1] % mod;
		ifact = 1ll * ifact * i % mod;
	}
}

vi left_tree[maxN];
vector<pii> tree_queries[maxN];
pii left_tree_ival[maxN];
vi right_tree[maxN];
int pre_right[maxN];
pii ival_tree[maxN];

pii ival_sons[maxN];
int ival_lca[maxN];
ll ival_cum[maxN];
int id_of_ord[maxN];
int left_tree_root[maxN];

int pre_cnt = 0;

void dfs_right(int v) {
	int new_pre = pre_cnt;
	pre_cnt += pre_right[v];
	pre_right[v] = new_pre;
	ival_tree[v] = {new_pre, pre_cnt};
	for (auto u : right_tree[v]) {
		dfs_right(u);
		ival_tree[v].nd = ival_tree[u].nd;
	}
}

const int inf = 1e9 + 2137;

struct Node {
	int l, r;
	int best_ord;
	Node(int ord) {
		l = r = -1;
		best_ord = ord;
	}
};

vector<Node> tree_nodes;

int path_from_root[100];
void find_and_remove(int root, int ord) {
	int l = 0, r = part_base - 1;
	int path_len = 0;
	while (l != r) {
		path_from_root[path_len ++] = root;
		int mid = (l + r) / 2;
		if (ord <= mid) {
			root = tree_nodes[root].l;
			r = mid;
		} else {
			root = tree_nodes[root].r;
			l = mid + 1;
		}
	}
	tree_nodes[root].best_ord = inf;
	while (path_len > 0) {
		root = path_from_root[-- path_len];
		tree_nodes[root].best_ord = inf;
		if (tree_nodes[root].l != -1 && tree_nodes[tree_nodes[root].l].best_ord < tree_nodes[root].best_ord)
			tree_nodes[root].best_ord = tree_nodes[tree_nodes[root].l].best_ord;
		if (tree_nodes[root].r != -1 && tree_nodes[tree_nodes[root].r].best_ord < tree_nodes[root].best_ord)
			tree_nodes[root].best_ord = tree_nodes[tree_nodes[root].r].best_ord;
	}
}

int find_lower_bound(int root, int ord) {
	int l = 0, r = part_base - 1;
	int res = inf;
	while (l != r) {
		int mid = (l + r) / 2;
		if (ord <= mid) {
			if (tree_nodes[root].r != -1 && tree_nodes[tree_nodes[root].r].best_ord < res)
				res = tree_nodes[tree_nodes[root].r].best_ord;
			if (tree_nodes[root].l != -1) {
				root = tree_nodes[root].l;
				r = mid;
			} else
				break;
		} else {
			if (tree_nodes[root].r != -1) {
				root = tree_nodes[root].r;
				l = mid + 1;
			} else
				break;
		}
	}
	if (l == r && tree_nodes[root].best_ord < res)
		res = tree_nodes[root].best_ord;
	return res;
}

void merge_trees(int root, int other) {
	if (tree_nodes[other].best_ord < tree_nodes[root].best_ord)
		tree_nodes[root].best_ord = tree_nodes[other].best_ord;
	if (tree_nodes[root].l == -1)
		tree_nodes[root].l = tree_nodes[other].l;
	else if (tree_nodes[other].l != -1)
		merge_trees(tree_nodes[root].l, tree_nodes[other].l);
	if (tree_nodes[root].r == -1)
		tree_nodes[root].r = tree_nodes[other].r;
	else if (tree_nodes[other].r != -1)
		merge_trees(tree_nodes[root].r, tree_nodes[other].r);
}

int create_tree(int ord) {
	int root_res = sz(tree_nodes);
	tree_nodes.push_back(Node(ord));
	int root = root_res;
	int l = 0, r = part_base - 1;
	while (l != r) {
		int son = sz(tree_nodes);
		tree_nodes.push_back(Node(ord));
		int mid = (l + r) / 2;
		if (ord <= mid) {
			tree_nodes[root].l = son;
			root = son;
			r = mid;
		} else {
			tree_nodes[root].r = son;
			root = son;
			l = mid + 1;
		}
	}
	return root_res;
}

void dfs_left(int v) {
	left_tree_root[v] = -1;
	for (auto u : left_tree[v]) {
		dfs_left(u);
		if (left_tree_root[u] == -1)
			continue;
		if (left_tree_root[v] == -1) {
			left_tree_root[v] = left_tree_root[u];
			continue;
		}
		merge_trees(left_tree_root[v], left_tree_root[u]);
	}
	for (auto [who, id] : tree_queries[v]) {
		int ord = pre_right[who] ++;
		id_of_ord[ord] = id;
		int root = create_tree(ord);
		if (left_tree_root[v] == -1) {
			left_tree_root[v] = root;
			continue;
		}
		merge_trees(left_tree_root[v], root);
	}
	if (left_tree_root[v] == -1)
		return;
	auto [l, r] = ival_tree[v];
	while (true) {
		int ord = find_lower_bound(left_tree_root[v], l);
		if (ord >= r)
			break;
		int id = id_of_ord[ord];
		ival_lca[id] = v;
		find_and_remove(left_tree_root[v], ord);
	}
}

const int big_base = (1 << 20);

int init_ival_tree[2 * big_base];

void put_ival(int l, int r, int k) {
	l += big_base;
	r += big_base;
	init_ival_tree[l] = init_ival_tree[r] = k;
	while (l / 2 != r / 2) {
		if (l % 2 == 0)
			init_ival_tree[l + 1] = k;
		if (r % 2 == 1)
			init_ival_tree[r - 1] = k;
		l /= 2;
		r /= 2;
	}
}

int get_ival(int p) {
	int res = 0;
	p += big_base;
	while (p) {
		if (init_ival_tree[p] > res)
			res = init_ival_tree[p];
		p /= 2;
	}
	return res;
}

int32_t main() {
   	ios_base::sync_with_stdio(0), cin.tie(0);
	int n;
	cin >> n;
	fwd(i, 1, n + 1) {
		int l, r;
		cin >> l >> r;
		l -= 1;
		r -= 1;
		ival_sons[i].st = get_ival(l);
		ival_sons[i].nd = get_ival(r);
		put_ival(l, r, i);
		left_tree[ival_sons[i].st].push_back(i);
		right_tree[ival_sons[i].nd].push_back(i);
		if (ival_sons[i].st == ival_sons[i].nd)
			ival_lca[i] = ival_sons[i].st;
		else {
			tree_queries[ival_sons[i].nd].push_back({ival_sons[i].st, i});
			pre_right[ival_sons[i].st] += 1;
		}
	}
	dfs_right(0);
	dfs_left(0);
	for (int i = n; i >= 1; i --) {
		ival_cum[i] += 1;
		ival_cum[ival_sons[i].st] += ival_cum[i];
		ival_cum[ival_sons[i].nd] += ival_cum[i];
		ival_cum[ival_lca[i]] -= ival_cum[i];
	}
	prep_inwers();
	int ans = 0;
	fwd(i, 1, n + 1) {
		ans += inwers[ival_cum[i]];
		if (ans >= mod)
			ans -= mod;
	}
	cout << ans << '\n';
   	return 0;
}