#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
struct Node {
  long long l, r;
} nodes[N];
int cmp(const Node a, const Node b) { return a.r < b.r; }
int main() {
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    int a, b;
    cin >> a >> b;
    nodes[i].l = max(0, a - b), nodes[i].r = a + b;
  }
  sort(nodes + 1, nodes + n + 1, cmp);
  int ans = 0, nowR = 0;
  for (int i = 1; i <= n; i++) {
    if (nodes[i].l < nowR) continue;
    nodes[i].r = nowR, ans++;
  }
  cout << ans;
  return 0;
}
