#include <iostream>
#include <vector>
using namespace std;
typedef long long ll;
# define d first
# define x second
void solve() {
ll n; cin >> n;
vector<pair<ll,ll>> a(n);
for (auto &x : a) cin >> x.d >> x.x;
vector<ll> dp(n, 1);
for (ll i = n - 1; i >= 0; i--) {
if (a[i].d == 0) continue;
for (ll j = i + a[i].d, cnt = 1; j < n and cnt <= a[i].x; j += a[i].d, cnt++) dp[i] += dp[j];
}
cout << dp[0];
}
int main() {
//freopen("filename.in", "r", stdin), freopen("filename.out", "w", stdout);
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int t = 1; //cin >> t;
while (t--) solve();
}
