#include <bits/stdc++.h>
using namespace std;
const int MAXN = 5e5 + 25;
int x[MAXN], e[MAXN], n;
vector <int> adj[MAXN], radj[MAXN];
bool vis[MAXN];
vector <int> kosaraju;
void dfs (int pos) {
vis[pos] = 1;
for (auto j : adj[pos]) {
if (!vis[j]) dfs(j);
}
kosaraju.push_back(pos);
}
int comp[MAXN], cnt;
void dfs2 (int pos, int c) {
comp[pos] = c; vis[pos] = 1;
for (auto j : radj[pos]) {
if (!vis[j]) {
dfs2(j, c);
}
}
}
int deg[MAXN];
int main () {
ios::sync_with_stdio(0); cin.tie(0);
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 (abs(x[i] - x[j]) <= e[i] - e[j]) {
adj[i].push_back(j);
radj[j].push_back(i);
}
}
}
for (int i = 1; i <= n; i++) {
if (!vis[i]) dfs(i);
}
reverse(kosaraju.begin(), kosaraju.end());
memset(vis, 0, sizeof(vis));
for (auto i : kosaraju) {
if (!vis[i]) {
dfs2(i, ++cnt);
}
}
for (int i = 1; i <= n; i++) {
for (auto j : adj[i]) {
if (comp[j] == comp[i]) continue;
deg[j]++;
}
}
int ans = 0;
for (int i = 1; i <= cnt; i++) if (!deg[i]) {
ans++;
}
cout << ans << '\n';
}
