#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
#define int long long
#define vel vector<long long>
#define V vector
#define ll long long
#define rep(i,n) for(int i=0;i<n;i++)
int pr = 1000000007;
void uni(vel &a) {
vel ans(1, a[0]);
int n = a.size();
rep(i, n - 1) { if (a[i + 1] != a[i]) { ans.push_back(a[i + 1]); } }
a = ans;
}
int rui(int a, int n) {
if (n == 0) { return 1; }
int back = rui(a, n / 2);
back *= back; back %= pr;
if (n % 2 == 0) { return back; }
return (back*a) % pr;
}
int inv(int a) {
return rui(a, pr - 2);
}
signed main() {
ll n; cin >> n;
vel a(n);
vel b(n);
vel all_time(1, 0);
rep(i, n) {
cin >> a[i] >> b[i]; b[i]++;
all_time.push_back(a[i]);
all_time.push_back(b[i]);
}
sort(all_time.begin(), all_time.end());
uni(all_time);
int sz = all_time.size();
vel gap(sz - 1);
rep(i, sz - 1) { gap[i] = all_time[i + 1] - all_time[i]; }
vel count(sz - 1);
rep(i, n) {
a[i] = lower_bound(all_time.begin(), all_time.end(), a[i]) - all_time.begin();
b[i] = lower_bound(all_time.begin(), all_time.end(), b[i]) - all_time.begin();
rep(j, b[i] - a[i]) {
count[a[i] + j]++;
}
}
V<vel> com(sz - 1);
rep(i, sz - 1) {
int ba = 1;
rep(j, count[i]) {
ba *= gap[i] - j; ba %= pr;
ba *= inv(j + 1); ba %= pr;
com[i].push_back(ba);
}
}
V<V<vel>> dp1(2);
rep(i, 2) {
rep(j, sz - 1) {
dp1[i].push_back(vel(count[j], 0));
}
}
vel now_count(sz - 1, 0);
rep(i, n) {
int now = i % 2;
int nex = (i + 1) % 2;
dp1[nex] = dp1[now];
int sum = 1;
rep(j, a[i]) {
rep(k, now_count[j]) {
sum += dp1[now][j][k] * com[j][k];
sum %= pr;
}
}
for (int j = a[i]; j < b[i]; j++) {
dp1[nex][j][0] += sum; dp1[nex][j][0] %= pr;
rep(k, now_count[j]) {
dp1[nex][j][k + 1] += dp1[now][j][k]; dp1[nex][j][k + 1] %= pr;
sum += dp1[now][j][k] * com[j][k];
sum %= pr;
}
now_count[j]++;
}
}
ll ans = 0;
rep(i, sz - 1) {
rep(k, count[i]) {
ans += dp1[n % 2][i][k] * com[i][k];
ans %= pr;
}
}
cout << ans << endl;
return 0;
}
