#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define INF 50000000000009999ll
using ld = long double;
using ull = unsigned long long;
bool cmp(pair<int,int> a,pair<int,int> b)
{
if(a.second==b.second)
return a.first<b.first;
return a.second < b.second;
}
int main() {
int n;
cin>>n;
vector<pair<int,int>> arr(n);
for(int i=0;i<n;i++)
{
int r,c;
cin>>c>>r;
arr[i].first = c-r;
arr[i].second = c+r;
}
sort(arr.begin(),arr.end(),cmp);
int cnt=0,cur=arr[0].second;
for(int i=1;i<n;i++)
{
if(arr[i].first > cur)
{
cur=arr[i].second;
}
else
cnt++;
}
cout<<cnt;
return 0;
}