#include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <algorithm>
#include <set>
#include <queue>
#include <map>
#include <stack>
#include <bitset>
#include <string>
#include <cstring>
#include <iterator>
#include <random>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
const ll dim = 1e6+7;
//const ll mod = 1e9 + 7;
const ll inf = 1e18 + 77;
#define endl "\n"
#define fi first
#define pb push_back
#define se second
#define vll vector<ll>
ll n, l;
ll x[dim], e[dim];
pair<ll, ll> a[dim];
int main() {
set<pll> s;
cin>>n;
multiset<ll> rt, lt;
for(int i=1; i<=n; i++) {
cin>>x[i]>>e[i];
s.insert({x[i], e[i]});
}
n=s.size();
ll id=1;
for(auto el: s){
a[id]=el;
rt.insert({el.se-el.fi});
id++;
}
ll ans=0;
for(int i=1; i<=n; i++){
ll e=a[i].se;
ll x=a[i].fi;
ll fl=0;
rt.erase(rt.find(e-x));
if(rt.size()>0){
auto it=rt.upper_bound(e-x);
if(it==rt.end()){
it--;
ll val=(*it);
// cout<<e-x<<" "<<val<<endl;
if(val>=e-x)fl=1;
}
else fl=1;
}
if(lt.size()>0){
auto it=lt.upper_bound(e+x);
if(it==lt.end()){
it--;
ll val=(*it);
// cout<<e+x<<" "<<val<<endl;
if(val>=e+x)fl=1;
}
else fl=1;
}
// cout<<endl;
lt.insert(e+x);
if(fl==0)ans++;
}
cout<<ans<<endl;
return 0;
}
