#include <bits/stdc++.h>
using namespace std;
#define int long long
const int m = 1e9 + 7;
int n, dp[100005];
pair<int, int> a[100005];
int32_t main() {
ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cin >> n;
for (int i = 1; i <= n; i++) cin >> a[i].first >> a[i].second;
dp[1] = 1;
for (int i = 2; i <= n; i++) {
for (int j = 1; j < i; j++) {
if (a[j].first == 0) continue;
int d = i - j;
if (d % a[j].first == 0
&& (d / a[j].first) <= a[j].second)
dp[i] = (dp[i] + dp[j]) % m;
}
}
int ans = 0;
for (int i = 1; i <= n; i++) ans = (ans + dp[i]) % m;
cout << ans;
}
