#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<pair<long long,long long>> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i].first >> a[i].second;
}
sort(a.begin(), a.end());
vector<pair<long long,long long>> b;
for (int i = 0; i < n; ) {
int j = i;
long long x = a[i].first;
long long mx = a[i].second;
while (j < n && a[j].first == x) {
mx = max(mx, a[j].second);
j++;
}
b.push_back({x, mx});
i = j;
}
int m = (int)b.size();
vector<long long> x(m + 2), e(m + 2);
for (int i = 1; i <= m; i++) {
x[i] = b[i - 1].first;
e[i] = b[i - 1].second;
}
const long long NEG = -(1LL << 60);
vector<long long> pref(m + 2, NEG), suff(m + 2, NEG);
for (int i = 1; i <= m; i++) {
pref[i] = max(pref[i - 1], x[i] + e[i]);
}
for (int i = m; i >= 1; i--) {
suff[i] = max(suff[i + 1], e[i] - x[i]);
}
int ans = 0;
for (int i = 1; i <= m; i++) {
bool bad = false;
if (pref[i - 1] >= x[i] + e[i]) bad = true;
if (suff[i + 1] >= e[i] - x[i]) bad = true;
if (!bad) ans++;
}
cout << ans << '\n';
return 0;
}
