#include <bits/stdc++.h>
#define pb push_back
#define ll long long int
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
using namespace std;
int n;
set<int> adj[100005];
vector<ll> ans(100005);
int main() {
cin >> n;
for (int i = 1; i <= n; i++) {
ll d, x; cin >> d >> x;
for (int j = 1; d > 0 && j <= x && i+j*d <= n; j++) {
adj[i+j*d].insert(i+(j-1)*d);
}
}
ll cur = 0; ans[1] = 1;
for (int i = 1; i <= n; i++) {
for (auto j : adj[i]) {
ans[i] += ans[j]; ans[i] %= (ll)1e9+7;
}
cur += ans[i]; cur %= (ll)1e9+7;
}
cout << cur;
return 0;
}
