#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
// #define int long long
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
const int N = 5e5 + 5;
int X[N] = {}, E[N] = {};
signed main(){
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int n; cin >> n;
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);
}
map<int, int> vis;
int ans = 0;
ordered_set idx1, idx2;
for (auto i : a){
if (vis[X[i]]) continue;
int it1 = idx1.order_of_key(X[i]);
int it2 = idx2.order_of_key(-X[i]);
bool F = 0;
if (it1 != 0){
auto it = idx1.find_by_order(it1 - 1);
int j = *it;
j = best[j];
if (abs(X[j] - X[i]) <= E[j] - E[i]){
F = 1;
vis[X[i]] = 1;
}
}
if (it2 != 0){
auto it = idx2.find_by_order(it2 - 1);
int j = *it;
j = best[j * -1];
if (abs(X[j] - X[i]) <= E[j] - E[i]){
F = 1;
vis[X[i]] = 1;
}
}
if (!F) {
ans++;
vis[X[i]] = 1;
idx1.insert(X[i]);
idx2.insert(-X[i]);
}
}
cout << ans << endl;
}
