#include <bits/stdc++.h>
#define int long long
using namespace std;
const int INF = 1e18;
struct NodeMax {
long long seg_max;
static NodeMax merge(NodeMax a, NodeMax b) { return {max(a.seg_max, b.seg_max)}; }
static NodeMax zero_el() { return {-INF}; }
};
template <class Node>
struct SegTree {
vector<Node> t;
int n, h = 1;
SegTree(const int& sz) : SegTree(vector<Node>(sz, Node::zero_el())) {}
SegTree(vector<Node> in) {
n = in.size();
while (1 << h < n)
h += 1;
t.resize(1 << (h + 1), Node::zero_el());
for (int i = (1 << h); i < (1 << h) + n; ++i)
t[i] = in[i - (1 << h)];
for (int i = (1 << h) - 1; i > 0; --i)
t[i] = Node::merge(t[i << 1], t[(i << 1) | 1]);
}
void upd(int v, int v_l, int v_r, int i, Node val) {
if (i < v_l || i >= v_r)
return;
if (v_l + 1 == v_r) {
t[v] = val;
return;
}
int v_m = (v_l + v_r) / 2;
upd((v << 1), v_l, v_m, i, val);
upd(((v << 1) | 1), v_m, v_r, i, val);
t[v] = Node::merge(t[v << 1], t[(v << 1) | 1]);
}
void upd(int i, Node val) { upd(1, 0, (1 << h), i, val); }
Node get(int v, int v_l, int v_r, int l, int r) {
if (v_l >= r || v_r <= l)
return Node::zero_el();
if (l <= v_l && v_r <= r)
return t[v];
int v_m = (v_l + v_r) / 2;
return Node::merge(get((v << 1), v_l, v_m, l, r), get(((v << 1) | 1), v_m, v_r, l, r));
}
Node get(int l, int r) { return get(1, 0, (1 << h), l, r); }
Node get_by_id(int i) { return t[(1 << h) + i - 1]; };
};
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0);
int n;
cin >> n;
vector<pair<int, int>> a(n);
vector<int> xs;
for (auto& [ei, xi] : a) {
cin >> xi >> ei;
xs.push_back(xi);
}
sort(xs.begin(), xs.end());
xs.resize(unique(xs.begin(), xs.end()) - xs.begin());
map<int, int> xcomp;
for (int i = 0; i < xs.size(); ++i)
xcomp[xs[i]] = i;
for (auto& [ei, xi] : a)
xi = xcomp[xi];
sort(a.begin(), a.end(), greater<>());
SegTree<NodeMax> preft(xs.size()), sufft(xs.size());
int ans = 0;
for (int i = 0; i < n; ++i) {
int prefmx = preft.get(0, a[i].second + 1).seg_max;
if (prefmx >= a[i].first + xs[a[i].second])
continue;
int suffmx = sufft.get(a[i].second, xs.size()).seg_max;
if (suffmx >= a[i].first - xs[a[i].second])
continue;
ans += 1;
preft.upd(a[i].second, {a[i].first + xs[a[i].second]});
sufft.upd(a[i].second, {a[i].first - xs[a[i].second]});
}
cout << ans;
}
