#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;
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; }
set<pair<int, int>> q; for (int i = 0; i < n; i++) { int x, y; cin >> x >> y; q.insert({x, y}); }
vector<pair<int, int>> p; for (auto x: q) p.push_back(x);
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;
}
