#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
#define F first
#define S second
using namespace std;
using ll = long long;
#include <bits/stdc++.h>
using namespace std;
void counting_sort(vector<pair<int,int>> &a, int exp, int base) {
int n = a.size();
vector<pair<int,int>> output(n);
vector<int> count(base, 0);
for (int i = 0; i < n; i++) {
int digit = (a[i].first / exp) % base;
count[digit]++;
}
for (int i = 1; i < base; i++) {
count[i] += count[i - 1];
}
for (int i = n - 1; i >= 0; i--) {
int digit = (a[i].first / exp) % base;
output[count[digit] - 1] = a[i];
count[digit]--;
}
a = move(output);
}
void radix_sort_pairs(vector<pair<int,int>> &a) {
if (a.empty()) return;
int mx = 0;
for (auto &p : a) mx = max(mx, p.first);
int base = 10;
for (int exp = 1; mx / exp > 0; exp *= base) {
counting_sort(a, exp, base);
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cout << fixed << setprecision(0);
int n, ans = 0; cin >> n; if (n == 1) { cout << 1; return 0; }
vector<pair<int, int>> p(n); for (int i = 0; i < n; i++) cin >> p[i].F >> p[i].S;
radix_sort_pairs(p);
vector<int> a(n), b(n), maxal(n), minbr(n);
for (int i = 0; i < n; i++) a[i] = p[i].F + p[i].S, b[i] = p[i].F - p[i].S;
maxal[0] = a[0]; minbr[n - 1] = b[n - 1];
for (int i = 1; i < n; i++) maxal[i] = max(maxal[i - 1], a[i]);
for (int i = n - 2; i >= 0; i--) minbr[i] = min(minbr[i + 1], b[i]);
ans += (b[0] < minbr[1]) + ((a[n - 1] > maxal[n - 2]));
for (int i = 1; i < n - 1; i++) ans += (b[i] < minbr[i + 1] && a[i] > maxal[i - 1]);
cout << ans;
}
