#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
template <class T>
struct fenwick_ma{
int n;
vector<T> tree;
fenwick_ma(int _n){
n = _n;
tree = vector<T>(n,-1);
}
void update(int i,T v){
for(;i < n;i |= (i + 1)){
tree[i] = max(tree[i],v);
}
}
T query(int i){
T ans = -1;
for(;i >= 0;i = (i & (i + 1)) - 1){
ans = max(ans,tree[i]);
}
return ans;
}
};
template <class T>
struct fenwick_mi{
int n;
vector<T> tree;
fenwick_mi(int _n){
n = _n;
tree = vector<T>(n,INT_MAX);
}
void update(int i,T v){
for(;i >= 0;i = (i & (i + 1)) - 1){
tree[i] = min(tree[i],v);
}
}
T query(int i){
T ans = INT_MAX;
for(;i < n;i |= (i + 1)){
ans = min(ans,tree[i]);
}
return ans;
}
};
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
vector<pair<int,int>> a(n);
vector<int> su(n),di(n);
for(int i = 0;i < n;i++){
cin >> a[i].first >> a[i].second;
su[i] = a[i].first + a[i].second;
di[i] = a[i].first - a[i].second;
}
vector<int> ind(n);
iota(ind.begin(),ind.end(),0);
sort(ind.begin(),ind.end(),[&](int i,int j){
return a[i].second < a[j].second;
});
int ans = 0;
fenwick_ma<int> fma(n + 1);
fenwick_mi<int> fmi(n + 1);
for(int i = n - 1;i >= 0;i--){
bool ok = false;
int e = ind[i];
int maxi = fma.query(e - 1);
int mini = fmi.query(e + 1);
if(maxi >= su[e]) ok = true;
if(mini <= di[e]) ok = true;
if(!ok){
fma.update(e,su[e]);
fmi.update(e,di[e]);
ans ++;
}
}
cout << ans << '\n';
return 0;
}
