#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; 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].first >> p[i].second;
vector<int> a(n), b(n);
for (int i = 0; i < n; i++) a[i] = p[i].first + p[i].second, b[i] = p[i].first - p[i].second;
vector<int> maxal(n); maxal[0] = a[0];
for (int i = 1; i < n; i++) maxal[i] = max(maxal[i - 1], a[i]);
vector<int> minbr(n); minbr[n - 1] = b[n - 1];
for (int i = n - 2; i >= 0; i--) minbr[i] = min(minbr[i + 1], b[i]);
vector<int> ans(n, 0);
if (b[0] >= minbr[1]) ans[0] = 0; else ans[0] = 1;
if (a[n - 1] <= maxal[n - 2]) ans[n - 1] = 0; else ans[n - 1] = 1;
for (int i = 1; i < n - 1; i++)
if (b[i] >= minbr[i + 1] || a[i] <= maxal[i - 1]) ans[i] = 0;
else ans[i] = 1;
int ret = 0; for (auto x: ans) ret += x;
cout << ret;
}
