#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::steady_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
const int MAXN = 5e5 + 7;
pll vec[MAXN];
bool bad[MAXN];
int n;
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n;
map<ll ,ll> lol;
for(int i = 1; i <= n; i++){
cin >> vec[i].fi >> vec[i].se;
lol[vec[i].fi] = max(lol[vec[i].fi], vec[i].se);
}
n = sz(lol);
int wsk = 1;
for(auto ele : lol){
vec[wsk] = ele;
wsk++;
}
ll mx = -1e18;
for(int i = 1; i <= n; i++){
if((ll)vec[i].fi + vec[i].se <= mx){
bad[i] = 1;
}
mx = max(mx, (ll)vec[i].fi + vec[i].se);
}
mx = 1e18;
for(int i = n; i >= 1; i--){
if((ll)vec[i].fi - vec[i].se >= mx){
bad[i] = 1;
}
mx = min(mx, (ll) vec[i].fi - vec[i].se);
}
int ans = 0;
for(int i = 1; i <= n; i++){
if(!bad[i]){
ans++;
}
}
cout << ans << '\n';
return 0;
}
