#include <bits/stdc++.h>
using namespace std;
long long n;
double t, ans, x, y;
map<pair<double, double>, bool> b;
pair<double, double> p[1005];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> t;
  for (int i = 1; i <= n; i++) {
    cin >> x >> y;
    p[i].first = x - y / 2;
    p[i].second = x + y / 2;
  }
  sort(p + 1, p + 1 + n);
  p[0].second = -1e18;
  for (int i = 1; i <= n; i++) {
    if (p[i].first - p[i - 1].second >= t &&
        b[{p[i].first - t, p[i].first}] == false) {
      b[{p[i].first - t, p[i].first}] = true;
      ans++;
    }
    if (p[i].second + t <= p[i + 1].first) {
      b[{p[i].second, p[i].second + t}] = true;
      ans++;
    }
  }
  ans++;
  cout << ans << '\n';
  return 0;
}
