#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
vector<pair<int, int>> a(n);
for (auto & [x, y]: a) {
cin >> x >> y;
auto x1 = x - y;
auto y1 = x + y;
x = x1;
y = y1;
}
sort(a.begin(), a.end());
// find upper hull
vector<pair<int, int>> b;
for (auto [x, y]: a) {
if (b.size() && b.back().first == x && b.back().second <= y) b.pop_back();
if (!b.size() || y > b.back().second) b.push_back({x, y});
}
cout << b.size() << '\n';
return 0;
}
