#include <bits/stdc++.h>
using namespace std;
int n;
long long x[1005], e[1005];
vector<int> g[1005], rg[1005];
vector<int> order;
int vis[1005];
int comp[1005];
int indeg[1005];
void dfs1(int u) {
vis[u] = 1;
for (int v : g[u]) {
if (!vis[v]) dfs1(v);
}
order.push_back(u);
}
void dfs2(int u, int c) {
comp[u] = c;
for (int v : rg[u]) {
if (!comp[v]) dfs2(v, c);
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> x[i] >> e[i];
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (i == j) continue;
if (llabs(x[i] - x[j]) <= e[i] - e[j]) {
g[i].push_back(j);
rg[j].push_back(i);
}
}
}
for (int i = 1; i <= n; i++) {
if (!vis[i]) dfs1(i);
}
reverse(order.begin(), order.end());
int cnt = 0;
for (int u : order) {
if (!comp[u]) {
cnt++;
dfs2(u, cnt);
}
}
for (int u = 1; u <= n; u++) {
for (int v : g[u]) {
if (comp[u] != comp[v]) {
indeg[comp[v]]++;
}
}
}
int ans = 0;
for (int i = 1; i <= cnt; i++) {
if (indeg[i] == 0) ans++;
}
cout << ans << '\n';
return 0;
}
