#include <bits/stdc++.h>
using namespace std;
int n;
int solve(int i, int last_picked_ind, vector<pair<int, int>>& ranges){
// check if we can pick this one
if(i >= n) return 0;
int l = ranges[i].first; int r = ranges[i].second;
if(last_picked_ind >= i - l) return solve(i + 1, last_picked_ind, ranges);
// pick or dont pick
int pick = 1 + solve(i + r + 1, i, ranges);
int dont = solve(i + 1, last_picked_ind, ranges);
return max(pick, dont);
}
int main(){
cin.tie(0);
ios::sync_with_stdio(0);
cin >> n;
vector<pair<int, int>> tulips(n);
for(int i = 0; i < n; i++){
cin >> tulips[i].first >> tulips[i].second;
}
cout << solve(0, INT_MIN, tulips) << "\n";
}
