#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
void solve(){
int n; cin >> n;
int X[n + 1] = {}, E[n + 1] = {};
bool Sub1 = 1, Sub2 = (n <= 16);
map<int, int> MA;
for (int i = 1; i <= n; i++){
cin >> X[i] >> E[i];
if (MA[X[i]] == 0 or E[MA[X[i]]] < E[i]) MA[X[i]] = i;
if (i > 1 && E[i] != E[i - 1]) Sub1 = 0;
}
map<int, vector<int>> C;
int ans = 0;
vector<int> a;
for (int i = 1; i <= n; i++){
C[E[i]].push_back(i);
if (C[E[i]].size() == 1) a.push_back(E[i]);
}
int vis[n + 1] = {};
sort(rbegin(a), rend(a));
set<int> idx1, idx2;
for (auto v : a){
for (auto i : C[v]){
auto it1 = lower_bound(idx1.begin(), idx1.end(), X[i]);
auto it2 = lower_bound(idx2.begin(), idx2.end(), -X[i]);
if (idx1.size() && it1 != idx1.end()){
int x = *it1;
int j = MA[x];
// cout << i << ' ' << j << endl;
if (abs(X[j] - X[i]) <= E[j] - E[i]) vis[i] = 2;
}
if (idx2.size() && it2 != idx2.end()){
int x = *it2;
x *= -1;
int j = MA[x];
if (abs(X[j] - X[i]) <= E[j] - E[i]) vis[i] = 2;
// cout << i << ' ' << j << endl;
}
if (vis[i] == 0){
// cout << i << endl;
idx1.insert(X[i]);
idx2.insert(-X[i]);
vis[i] = 1;
ans++;
}
}
}
cout << ans << endl;
}
signed main(){
int tc = 1;
// cin >> tc;
while (tc--){
solve();
}
}
