#include <bits/stdc++.h>
#define uwu return 0;
using namespace std;
const int SIZE = 5e5 + 5;
int N;
int X[SIZE], E[SIZE];
int innode[SIZE];
map<int, pair<int, int>> mp;
#define fs first
#define sc second
vector<int> disX;
int main(){
cin >> N;
for (int i = 0; i < N;i++){
cin >> X[i] >> E[i];
if(mp[X[i]].fs < E[i]){
mp[X[i]].fs = E[i];
mp[X[i]].sc = 1;
}
}
for(auto i:mp){
disX.push_back(i.fs);
}
N = disX.size();
set<int> XmE, XpE;
for (int i = 0; i < N;i++){
if(XpE.lower_bound(disX[i] + mp[disX[i]].fs) != XpE.end()){
innode[i]++;
}
XpE.insert(disX[i] + mp[disX[i]].fs);
}
for (int i = N - 1; i >= 0;i--){
if(XmE.upper_bound(disX[i] - mp[disX[i]].fs) != XmE.begin()){
innode[i]++;
}
XmE.insert(disX[i] - mp[disX[i]].fs);
}
int cnt = 0;
for (int i = 0; i < N;i++){
//cout << innode[i] << '\n';
if(!innode[i])
cnt += mp[disX[i]].sc;
}
cout << cnt << '\n';
}
