//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int INF = 1e17;
struct node {
int maxx_val = -INF;
node *left ;
node *right;
node() {
maxx_val = -INF;
left = 0;
right = 0;
}
node * go_to_l() {
if (!left) left = new node();
return left;
}
node * go_to_r() {
if (!right) right = new node();
return right;
}
};
void upd(node *u,int l,int r,int val,int pos) {
if (r - l == 1) {
u->maxx_val = max(val,u->maxx_val);
return;
}
int mid = (l + r) / 2;
if (pos < mid) {
upd(u->go_to_l(),l,mid,val,pos);
}else {
upd(u->go_to_r(),mid,r,val,pos);
}
u->maxx_val = max(u->go_to_l()->maxx_val,u->go_to_r()->maxx_val);
}
int get(node *u,int l,int r,int ql,int qr) {
if (r <= ql || l >= qr) return -INF;
if (l >= ql && r <= qr) return u->maxx_val;
int mid = (l + r) / 2;
return max(get(u->go_to_l(),l,mid,ql,qr),get(u->go_to_r(),mid,r,ql,qr));
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
vector <pair<int,int>> vec(n);
for (int i = 0;i < n;i++) {
cin >> vec[i].second >> vec[i].first;
}
sort(vec.begin(), vec.end());
int ans = 0;
node* root1 = new node();
node* root2 = new node();
int L = 0;
int R = 1e10;
for (int i = n - 1;i >= 0;i--) {
int v1 = vec[i].first + vec[i].second;
int v2 = vec[i].first - vec[i].second;
int var1 = get(root1,L,R,0,vec[i].second);
int var2 = get(root2,L,R,vec[i].second,R);
if (v1 > var1 && v2 > var2) {
ans++;
}
upd(root1,L,R,v1,vec[i].second);
upd(root2,L,R,v2,vec[i].second);
}
cout << ans << '\n';
}
