#include<bits/stdc++.h>
using namespace std;
const int MX = 505;
const int Mod = 1e9 + 7;
int a[MX], b[MX];
int dp[MX][MX];
int n;
int solve(int i, int prev) {
if(i>n) return (prev!=0);
int &ret = dp[i][prev];
if(ret!=-1) return ret;
ret = solve(i+1, prev);
if(b[i]>a[prev]) ret = (ret+solve(i+1, i))%Mod;
return ret;
}
void PlayGround() {
cin >> n;
for(int i=1; i<=n; ++i) {
cin >> a[i] >> b[i];
}
memset(dp, -1, sizeof dp);
cout << solve(1, 0) << endl;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
PlayGround();
return 0;
}
