#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define ppb pop_back
#define ep insert
#define endl '\n'
#define elif else if
#define pow pwr
#define sqrt sqrtt
#define int long long
#define ll long long
#define y1 YONE
typedef unsigned long long ull;
using namespace std;
const int N=1e5+5;
int dp[N],d[N],x[N],n;
int32_t main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
cin>>n;
for (int i=1;i<=n;i++) cin>>d[i]>>x[i];
for (int i=n;i;i--){
dp[i]=1;
if (!d[i]) continue;
for (int j=i+d[i];j<=min(n,i+d[i]*x[i]);j+=d[i]) dp[i]+=dp[j];
}
cout<<dp[1]<<endl;
return 0;
}
