#include <iostream>
#include <vector>
#include <stack>
#include <algorithm>
using namespace std;
const int MOD = 1'000'000'007;
struct Event {
int time;
int index;
bool isStart;
};
int main() {
int N;
cin >> N;
vector<int> A(N), B(N);
vector<Event> events;
for (int i = 0; i < N; ++i) {
cin >> A[i] >> B[i];
events.push_back({A[i], i, true});
events.push_back({B[i], i, false});
}
sort(events.begin(), events.end(), [](const Event &a, const Event &b) {
return a.time < b.time;
});
vector<vector<int>> dp(1, vector<int>(1, 1));
for (const auto &e : events) {
int n = dp.size();
int m = dp[0].size();
vector<vector<int>> new_dp(n + 1, vector<int>(m + 1, 0));
if (e.isStart) {
for (int i = 0; i < n; ++i)
for (int j = 0; j < m; ++j) {
new_dp[i + 1][j] = (new_dp[i + 1][j] + dp[i][j]) % MOD;
new_dp[i][j + 1] = (new_dp[i][j + 1] + dp[i][j]) % MOD;
}
} else {
for (int i = 0; i < n; ++i)
for (int j = 0; j < m; ++j) {
if (i > 0)
new_dp[i - 1][j] = (new_dp[i - 1][j] + dp[i][j]) % MOD;
if (j > 0)
new_dp[i][j - 1] = (new_dp[i][j - 1] + dp[i][j]) % MOD;
}
}
dp = move(new_dp);
}
cout << dp[0][0] << endl;
return 0;
}
