#include <bits/stdc++.h>
#define int long long
#define mp make_pair
#define pb push_back
#define ld long double
#define pii pair<int,int>
#define sz(x) (int)x.size()
#define piii pair<pii,pii>
#define precise cout<<fixed<<setprecision(10)
#define st first
#define nd second
#define ins insert
#define vi vector<int>
#define BOOST ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
using namespace std;
const int MAX=5e5+5;
int x[MAX],e[MAX];
bool cmp(int i,int j){
if (e[i]!=e[j])return e[i]>e[j];
return x[i]<x[j];
}
bool O[MAX];
bool check(int i,int j){
return e[i]-e[j]>=abs(x[i]-x[j]);
}
int32_t main()
{
BOOST;
int n;
cin>>n;
vi pom;
for (int i=1;i<=n;i++)pom.pb(i);
for (int i=1;i<=n;i++)cin>>x[i]>>e[i];
sort(pom.begin(),pom.end(),cmp);
int ans=0;
for (auto it:pom){
if (O[it])continue;
O[it]=true;
ans++;
for (int i=1;i<=n;i++){
if (i==it)continue;
if (check(it,i))O[i]=true;
}
}
cout<<ans;
return 0;
}
