#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e3 + 10;
int x[MAXN], e[MAXN];
int deg[MAXN];
int main(){
cin.tie(0)->sync_with_stdio(0);
int n; cin >> n;
for(int i=0; i<n; i++) cin >> x[i] >> e[i];
vector<pair<pair<int, int>, int>> r;
for(int i=0; i<n; i++) r.push_back({{x[i], e[i]}, i});
sort(r.begin(), r.end());
vector<int> to_erase;
int last_x = -1, last_e = -1;
for(int i=0; i<n; i++){
if(r[i].first.first == last_x && r[i].first.second == last_e){
to_erase.push_back(i);
}
last_x = r[i].first.first;
last_e = r[i].first.second;
}
while(!to_erase.empty()){
swap(r[to_erase.back()], r.back());
r.pop_back();
to_erase.pop_back();
}
n = r.size();
for(int i=0; i<n; i++){
x[i] = r[i].first.first;
e[i] = r[i].first.second;
}
for(int i=0; i<n; i++){
for(int j=0; j<n; j++){
if(j == i) continue;
if(abs(x[i] - x[j]) <= e[i] - e[j]) deg[j] ++;
}
}
int ans = 0;
for(int i=0; i<n; i++) ans += (deg[i] == 0);
cout << ans << "\n";
return 0;
}
