#include<bits/stdc++.h>
#include<fstream>
using namespace std;
ifstream fin("WINTER.inp");
ofstream fout("WINTER.out");
#define ll long long
#define pb push_back
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define ld long double
#define vt vector
#include<fstream>
#define fi first
#define se second
#define pll pair<ll, ll>
#define pii pair<int, int>
const ld PI = 3.14159265359;
const ll mod = 1e9 + 7;
const int mxn = 5e5, mxm = 1e5, sq = 400;
const int base = (1 << 18);
const ll inf = 1e9;
const ld pre = 1e-6;
int n;
pll p[mxn + 1];
bool ok[mxn + 1];
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n;
vt<pll>p;
forr(i, 0, n){
int x, e; cin >> x >> e;
p.pb({e, x});
}
sort(p.begin(), p.end());
for(int i = 1; i < n; i++){
for(int j = i - 1; j >= 0; j--){
if(abs(p[i].se - p[j].se) <= p[i].fi - p[j].fi){
ok[j] = 1;
}
}
}
int ans = 0;
forr(i, 0, n){
ans += (!ok[i]);
}
cout << ans;
return(0);
}
