#include "bits/stdc++.h"
using namespace std;
#ifdef Nero
#include "Deb.h"
#else
#define deb(...)
#endif
const int md = (int) 1e9 + 7;
void add(int& a, int b) {
a += b;
if (a >= md) a -= md;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<int> a(n), b(n), c;
for (int i = 0; i < n; ++i) {
cin >> a[i] >> b[i];
for (int j = a[i]; j <= b[i]; ++j) {
c.push_back(j);
}
}
sort(c.begin(), c.end());
c.resize(unique(c.begin(), c.end()) - c.begin());
vector<int> dp(n);
for (int i : c) {
vector<int> pd(n);
for (int j = 0; j < n; ++j) {
pd[j] = dp[j];
dp[j] = 0;
}
int s = 1;
for (int j = 0; j < n; ++j) {
dp[j] = pd[j];
if (a[j] <= i && b[j] >= i) {
add(dp[j], s);
}
add(s, pd[j]);
}
}
int ans = 0;
for (int i = 0; i < n; ++i) {
add(ans, dp[i]);
}
cout << ans << '\n';
return 0;
}
