#include <bits/stdc++.h>
#define ll long long
#define pii pair<ll, ll>
#define rep(i, a, b) for(int i = int(a); i < int(b); i++)
#define ub(c, x) distance((c).begin(),lower_bound(c.begin(),c.end(), (x)))
#define ff first
#define ss second
#define N 200015
using namespace std;
const int inf = 1e9;
ll gcd(ll a, ll b){
if(b == 0) return 1;
return gcd(b, a % b);
}
ll n, m, s, t, l, k, ans = 0;
vector<pair<ll, ll>> G[N];
vector<ll> dijkstra(ll st){
priority_queue<pii, vector<pii>, greater<pii>> pq;
vector<ll> dis;
dis.resize(n + 1, 1e18);
dis[st] = 0;
pq.push({dis[st], st});
while(!pq.empty()){
pii now = pq.top();
pq.pop();
if(now.first != dis[now.second]) continue;
for(auto x: G[now.second]){
ll i = x.first, c = x.second;
if(dis[i] > now.first + c){
dis[i] = now.first + c;
pq.push({dis[i], i});
}
}
}
return dis;
}
void CP2(){
cin >> n >> m >> s >> t >> l >> k;
rep(i, 0, m){
ll a, b, c;
cin >> a >> b >> c;
G[a].push_back({b, c});
G[b].push_back({a, c});
}
vector<ll> dis1 = dijkstra(s);
vector<ll> dis2 = dijkstra(t);
vector<ll> dis3 = dis2;
//for(auto x: dis1) cout << x << ' '; cout << "\n\n";
//for(auto x: dis2) cout << x << ' '; cout << "\n\n";
if(dis1[t] <= k){
cout << n * (n - 1) / 2 << "\n"; return;
}
sort(dis2.begin(), dis2.end());
rep(i, 1, n + 1){
ll need = k - dis1[i] - l;
ll can = upper_bound(dis2.begin(), dis2.end(), need) - dis2.begin();
ans += can;
if(dis3[i] <= need) ans--;
}
cout << ans << "\n";
}
void SA2(){
int n;
cin >> n;
vector<int> a(n);
map<int, int> mp;
rep(i, 0, n){
cin >> a[i];
mp[a[i]] = i;
}
//rep(i, 0, n) cout << b[a[i]] << ' '; cout << "\n";
int i = 0;
while(i < n){
int x = a[i];
int y = mp[a[i]];
for(; i <= y; i++) cout << x << ' ';
}
}
void RT(){
ll n, t;
cin >> n >> t;
vector<ll> v(n);
rep(i, 0, n) cin >> v[i];
rep(i, 0, n) v[i] %= t;
sort(v.begin(), v.end());
ll len = v[n - 1] - v[0];
rep(i, 0, n - 1){
len = min(len, t - (v[i + 1] - v[i]));
}
cout << (len + 1) / 2;
}
void AD2(){
ll n;
cin >> n;
vector<pair<ll, ll>> c;
rep(i, 0, n){
ll a, b;
cin >> a >> b;
c.push_back({a - b, a + b});
}
sort(c.begin(), c.end());
reverse(c.begin(), c.end());
//for(auto x: c) cout << x.ff << ' ' << x.ss << '\n';
ll prev = INT_MIN, ans = 0ll;
for(auto x: c){
if(prev > x.ss){
ans++;
}
prev = max(prev, x.ss);
}
cout << ans;
}
int main() {
int tc = 1;
//cin >> tc;
while(tc--) AD2();
}
