#include <bits/stdc++.h>
using namespace std;
int n;
map<pair<int, int>, int> memo;
int calls = 0;
int solve(int i, vector<int>& dp, vector<pair<int, int>>& ranges){
if(dp[i] != -1) return dp[i];
if(i < 0) return 0;
int pick = 1;
int dont = solve(i - 1, dp, ranges);
if(i - ranges[i].first >= 0) pick += solve(i - ranges[i].first - 1, dp, ranges);
dp[i] = max(pick, dont);
return dp[i];
}
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;
}
vector<int> dp(n, -1);
dp[0] = 1;
cout << solve(n-1, dp, tulips) << "\n";
}
