#include <bits/stdc++.h>
using namespace std;
#define print(l) for(auto i:l) cout<<i<<" ";cout<<endl;
#define input(t,l,n) vector<t>l(n);for(int i = 0;i<n;i++)cin>>l[i];
#define int long long
#define pb push_back
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define all(l) l.begin(),l.end()
#define pii pair<int,int>
#define fi first
#define se second
const int M = 1e9+7;
const int inf = 1e18;
void io(){
#ifndef ONLINE_JUDGE
freopen("input.txt","r",stdin);
// freopen("outputf.in","w",stdout);
#endif
}
int bp(int x, int y, int p){
int res = 1;
x = x % p;
while (y > 0) {
if (y & 1)
res = (res * x) % p;
y = y >> 1;
x = (x * x) % p;
}
return res;
}
int MI(int n, int p){
return bp(n, p - 2, p);
}
int mul(int x,int y, int p){
return x * 1ull * y % p;
}
int di(int x,int y, int p){
return mul(x, MI(y, p), p);
}
map<int , vector<int>>adj;
map<int,int>give;
int n , m , k , q;
map<int,int>po;
map<int,int>inde;
void solve(int testcase_number){
cin>>n;
vector<pii>inp;
for(int i = 0;i<n;i++){
cin>>m>>k;
po[m] = max(po[m],k);
// inp.pb({m,k});
inde[m] = 0;
}
for(auto i:po){
inp.pb(i);
// cout<<i.fi<<" "<<i.se<<endl;
}
n = inp.size();
map<int,int>give;
for(int i = 0;i<n;i++){
for(int j = i+1;j<n;j++){
give[inp[i].fi]++;
// cout<<inp[i].fi<<" "<<inp[j].fi<<" "<<(int)(abs(inp[i].fi-inp[j].fi) <= inp[i].se-inp[j].se)<<endl;
if((int)(abs(inp[i].fi-inp[j].fi) <= (inp[i].se-inp[j].se))) adj[inp[i].fi].pb(inp[j].fi);
if((int)(abs(inp[i].fi-inp[j].fi) <= (inp[j].se-inp[i].se))) adj[inp[j].fi].pb(inp[i].fi);
// adj[inp[j].fi].pb({inp[i].fi,(int)(abs(inp[i].fi-inp[j].fi) <= (inp[j].se-inp[i].se))});
}
}
for(auto i:adj){
// print(i.se);
for(auto j:i.se){
inde[j]++;
// send[i.fi].insert(j);
// rec[j].insert(i.fi);
// give[i.fi]++;
// cout<<i.fi<<" "<<j<<endl;
}
}
int ans = 0;
for(auto i:inde){
if(i.se == 0){
ans++;
}
}
cout<<ans<<endl;
}
signed main(){
// io();
ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
cin.tie(0), cout.tie(0);
cout << fixed<<setprecision(9);
int t = 1;
// cin>>t;
for(int i = 1;i<=t;i++){
solve(i);
}
}
