#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
int n; cin >> n;
int X[n + 1] = {}, E[n + 1] = {};
map<int, int> ma, best;
for (int i = 1; i <= n; i++){
cin >> X[i] >> E[i];
ma[X[i]] = max(ma[X[i]], E[i]);
}
for (int i = 1; i <= n; i++){
if (ma[X[i]] == E[i]) best[X[i]] = i;
}
map<int, vector<int>> idx;
vector<int> iter;
for (int i = 1; i <= n; i++){
if (idx[E[i]].size() == 0) iter.push_back(E[i]);
idx[E[i]].push_back(i);
}
sort(iter.rbegin(), iter.rend());
vector<int> a;
for (auto i : iter){
for (auto j : idx[i]) a.push_back(j);
}
int ans = 0;
set<int> idx1, idx2;
for (auto i : a){
auto it1 = idx1.lower_bound(X[i]);
auto it2 = idx2.lower_bound(-X[i]);
bool F = 0;
if (it1 != idx1.end()){
int val = *it1;
int j = best[val];
if (abs(X[j] - X[i]) <= E[j] - E[i]) F = 1;
}
if (it2 != idx2.end()){
int val = *it2;
int j = best[-1 * val];
if (abs(X[j] - X[i]) <= E[j] - E[i]) F = 1;
}
if (!F) {
ans++;
idx1.insert(X[i]);
idx2.insert(-X[i]);
}
}
cout << ans << endl;
}
