#include <bits/stdc++.h>
using namespace std;
using ll = long long;
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<int> x(n), y(n), a(n), b(n), maxal(n), minbr(n);
for (int i = 0; i < n; i++) cin >> x[i] >> y[i];
for (int i = 0; i < n; i++) a[i] = x[i] + y[i], b[i] = x[i] - y[i];
maxal[0] = a[0]; for (int i = 1; i < n; i++) maxal[i] = max(maxal[i - 1], a[i]);
minbr[n - 1] = b[n - 1]; 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;
}
