#include <bits/stdc++.h>
#define fi first
#define se second
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pa;
const ll N = 1e7 + 100;
const ll MOD = 1e9 + 7;
const ll INF = 1e12;
int pr[N], suff[N];
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n;
cin >> n;
vector <pair <int, int>> v;
for (int i = 1; i <= n; i++) {
int x, y;
cin >> x >> y;
v.push_back({x, y});
}
pr[0] = v[0].fi + v[0].se;
for (int i = 1; i < n; i++) {
pr[i] = max(pr[i - 1], v[i].fi + v[i].se);
}
suff[n - 1] = v[n - 1].fi - v[n - 1].se;
for (int i = n - 2; i >= 0; i--) {
suff[i] = min(suff[i + 1], v[i].fi - v[i].se);
}
int cnt = 0;
if (suff[1] > v[0].fi - v[0].se)
cnt++;
if (pr[n - 2] < v[n - 1].fi + v[n - 1].se)
cnt++;
for (int i = 1; i < n - 1; i++) {
if (suff[i + 1] > v[i].fi - v[i].se && pr[i - 1] < v[i].fi + v[i].se) {
cnt++;
}
}
cout << cnt << '\n';
return 0;
}
// x(i) - x(j) <= y(i) - y(j)
// x(i) - y(i) <= x(j) - y(j)
// x(j) - x(i) <= y(i) - y(j)
// x(j) + y(j) <= x(i) + y(i)
