#include<bits/stdc++.h>
using namespace std;
#define optimizar_io ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);cout.setf(ios::fixed);cout.precision(15);
#pragma GCC optimize("Ofast")
typedef long long ll;
struct Segment_Tree{
typedef long long ll;
vector<ll> ST;
Segment_Tree(ll n){
ST.assign(2*(n+1),-1e17);
}
void update(ll a, ll b){
a+=ST.size()/2; ST[a]=b;
for(a/=2; a>0; a=a/2)
ST[a]=max(ST[a*2],ST[a*2+1]);
}
ll RMQ(ll a, ll b)
{
a += ST.size()/2; b += ST.size()/2;
ll s = -1e17;
while (a <= b) {
if (a%2 == 1) s = max(s,ST[a++]);
if (b%2 == 0) s = max(s,ST[b--]);
a /= 2; b /= 2;
}
return s;
}
};
int main()
{
ll n;
cin>>n;
vector<pair<ll,ll>> v(n),v2(n);
Segment_Tree l(n+2),r(n+2);
for(int i=0; i<n; i++){
cin>>v[i].second>>v[i].first;
v2[i].first=v[i].second;
v2[i].second=v[i].first;
}
sort(v.begin(),v.end());reverse(v.begin(),v.end());sort(v2.begin(),v2.end());
map<pair<ll,ll>, ll> mapa;
for(int i=0; i<n; i++)
{
swap(v2[i].first,v2[i].second);
mapa[v2[i]]=i+1;
}
ll cont=0;
for(int i=0; i<n; i++)
{ if(l.RMQ(1,mapa[v[i]])>=v[i].second+v[i].first||r.RMQ(mapa[v[i]],n)>=v[i].first-v[i].second);
else cont++;
l.update(mapa[v[i]],v[i].second+v[i].first);
r.update(mapa[v[i]],v[i].first-v[i].second);
}
cout<<cont;
return 0;
}
