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#include <iostream>
#include <vector>
#include <fstream>
#define ll long long
using namespace std;

const int M = 500005, mod = 1000000007;
int n, pol[2 * M], reach[M];
pair <int, int> graph[M];
bool vis[M];

ll pot(ll a, ll b) {
	if (b == 1)
		return a;
	ll res = pot(a, b / 2);
	res = res * res % mod;
	if (b % 2) {
		res *= a;
		res %= mod;
	}
	return res;
}

ll odw(ll a) {
	return pot(a, mod - 2);
}

void dfs(int v) {
	if (vis[v])
		return;
	vis[v] = 1;
	reach[v]++;
	dfs(graph[v].first);
	dfs(graph[v].second);
}

int32_t main() {
	cin.tie(0);
	cout.tie(0);
	ios_base::sync_with_stdio(0);
	//fstream cin("in.in");
	cin >> n;
	for (int i = 1; i <= n; i++) {
		int l, r;
		cin >> l >> r;
		graph[i] = { pol[l], pol[r] };
		for (int j = l; j <= r; j++)
			pol[j] = i;
	}
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j <= n; j++)
			vis[j] = 0;
		dfs(i);
	}
	ll res = 0;
	for (int i = 1; i <= n; i++)
		res = (res + odw(reach[i])) % mod;
	cout << res;
}