#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define F first
#define S second
template<typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p)
{
return os << "(" << p.F << "," << p.S << ")";
}
template<typename T>
void print(T v)
{
for(auto x : v)
cout << x << " ";
cout << "\n";
}
int main()
{
int n;
cin >> n;
vector<pair<int, int>> v(n);
for(auto &[d, x] : v) cin >> d >> x;
vector<ll> dp(n, 1);
for(int i = n - 1; i >= 0; i--)
{
auto [d, x] = v[i];
if(d == 0) continue;
for(int j = 1; j <= x; j++)
{
if(i + j * d >= n) break;
dp[i] += dp[i + j * d];
}
}
// print(dp);
cout << dp[0] << " ";
}
