#include <cassert> #include <iostream> using namespace std; const int mod = 1000000007; int n, a[509], b[509], dp[509]; int main() { cin >> n; for (int i = 0; i < n; i++) { cin >> a[i] >> b[i]; assert(a[i] == b[i]); } int sum = 0; for (int i = 0; i < n; i++) { dp[i] = 1; for (int j = 0; j < i; j++) { if (a[j] < a[i]) { dp[i] += dp[j]; if (dp[i] >= mod) dp[i] -= mod; } } sum += dp[i]; if (sum >= mod) sum -= mod; } cout << sum << '\n'; return 0; }