#include<bits/stdc++.h>
using namespace std;
int solve(int i,vector<int> &dp,vector<int> &l,vector<int> &r){
if(i==0) return dp[i]=1;
if(i<0) return 0;
if(dp[i]!=-1) return dp[i];
int ans = 0;
for(int j=i-l[i]-1;j>=0;j--){
if(j + r[j] < i) ans=max(ans,solve(j,dp,l,r));
}
return dp[i] = 1 + ans;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
vector<int> l(n);
vector<int> r(n);
int ans=0;
vector<int> dp(n,-1);
for(int i=0;i<n;i++){
cin >> l[i] >> r[i];
}
for(int i=0;i<n;i++){
ans = max(ans,solve(i,dp,l,r));
}
cout<<ans<<"\n";
}
