#include <bits/stdc++.h>
using namespace std;
template <typename T>
class fenwick {
public:
vector<T> fenw;
int n;
fenwick(int _n) : n(_n) {
fenw.resize(n);
}
void modify(int x, T v) {
while (x < n) {
fenw[x] += v;
x |= (x + 1);
}
}
T get(int x) {
T v{};
while (x >= 0) {
v += fenw[x];
x = (x & (x + 1)) - 1;
}
return v;
}
};
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
vector<int> x(n);
vector<int> y(n);
for (int i = 0; i < n; i++) {
int a, b;
cin >> a >> b;
x[i] = a - b;
y[i] = a + b;
}
vector<int> order(n);
iota(order.begin(), order.end(), 0);
sort(order.begin(), order.end(), [&](int i, int j) {
if (x[i] != x[j]) {
return x[i] < x[j];
} else {
return y[i] > y[j];
}
});
auto xs = y;
sort(xs.begin(), xs.end());
xs.erase(unique(xs.begin(), xs.end()), xs.end());
fenwick<int> fenw(n + 1);
int ans = 0;
for (int i : order) {
int v = (int) (lower_bound(xs.begin(), xs.end(), y[i]) - xs.begin());
if (fenw.get(n - v) == 0) {
ans += 1;
fenw.modify(n - v, +1);
}
}
cout << ans << '\n';
return 0;
}
