#include <bits/stdc++.h>
#define int int64_t
using namespace std;
void setIO() {
cin.tie(0)->sync_with_stdio(0);
}
bool pred(pair<int, int> &src, pair<int, int> &dest) {
return (abs(src.first - dest.first) <= src.second - dest.second);
}
void mark(int idx, vector<bool> &marked, vector<pair<int, int>> &points) {
if(marked[idx]) return;
marked[idx] = true;
for(int i = 0; i < idx; i++) {
if(marked[i] or !pred(points[idx], points[i])) continue;
mark(i, marked, points);
}
}
void solve() {
//cout << "zco";
int n;
cin >> n;
vector<pair<int, int>> points(n);
map<int, int> f;
bool flag = true;
for(auto &x : points) {
cin >> x.first >> x.second;
f[x.first]++;
}
for(int i = 1; i < n; i++) {
if(points[i].second != points[i-1].second) flag = false;
}
sort(points.begin(), points.end(), [](pair<int, int> &a, pair<int, int> &b) { return a.second < b.second; });
int ans = 0;
vector<bool> marked(n, false);
for(int i = n-1; i > -1; i--) {
if(marked[i]) continue;
mark(i, marked, points);
ans++;
}
cout << (flag ? f.size() : ans);
}
int32_t main() {
setIO();
solve();
return 0;
}
