#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 5e5;
int n, x[N + 5], e[N + 5], indx[N + 5];
struct node {
int v = -1e18;
node *lef = nullptr, *rig = nullptr;
void extend() { if (!lef) lef = new node(), rig = new node(); }
void update(int tl, int tr, int k, int x) {
if (tl == tr) v = max(v, x);
else {
extend();
int tm = (tl + tr)/2;
if (k <= tm) lef->update(tl, tm, k, x);
else rig->update(tm + 1, tr, k, x);
v = max(lef->v, rig->v);
}
}
int query(int tl, int tr, int l, int r) {
if (l > r) return -1e18;
else if (tl == l && tr == r) return v;
else {
extend();
int tm = (tl + tr)/2;
return max(lef->query(tl, tm, l, min(tm, r)), rig->query(tm + 1, tr, max(l, tm + 1), r));
}
}
} *low = new node(), *high = new node();
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for (int i = 1; i <= n; i++) cin >> x[i] >> e[i];
iota(indx + 1, indx + n + 1, 1ll);
sort(indx + 1, indx + n + 1, [&](int a, int b) { return pair<int, int>(e[a], x[a]) > pair<int, int>(e[b], x[b]); });
int ans = 0;
for (int i = 1; i <= n; i++) {
int curIndex = indx[i], lowMax = low->query(1, 1e9, 1, x[curIndex]), highMax = high->query(1, 1e9, x[curIndex], 1e9);
if (e[curIndex] + x[curIndex] > lowMax && e[curIndex] - x[curIndex] > highMax) ans++;
low->update(1, 1e9, x[curIndex], e[curIndex] + x[curIndex]);
high->update(1, 1e9, x[curIndex], e[curIndex] - x[curIndex]);
}
cout << ans << '\n';
return 0;
}
