#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];
ll bit[mxn + 1], bit2[mxn + 1];
ll get(int p){
ll ans = 3e9;
while(p){
ans = min(ans, bit[p]);
p -= p & (-p);
}
return(ans);
}
void upd(int p, ll v){
while(p <= n){
bit[p] = min(bit[p], v);
p += p & (-p);
}
}
ll get2(int p){
ll ans = -3e9;
while(p){
ans = max(ans, bit2[p]);
p -= p & (-p);
}
return(ans);
}
void upd2(int p, ll v){
while(p <= n){
bit2[p] = max(bit2[p], v);
p += p & (-p);
}
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n;
vt<pll>p;
vt<int>comp;
forr(i, 0, n){
int x, e; cin >> x >> e;
p.pb({e, x});
comp.pb(x);
}
sort(comp.begin(), comp.end());
sort(p.begin(), p.end());
for(int i = 1; i <= n; i++)bit[i] = 3e9;
for(int i = n - 1; i >= 0; i--){
int id = lower_bound(comp.begin(), comp.end(), p[i].se) - comp.begin() + 1;
ll res = get(n - id + 1); //cout << res << " ";
if(res <= p[i].se - p[i].fi){
ok[i] = 1;
}
upd(n - id + 1, p[i].se - p[i].fi);
}
for(int i = 1; i <= n; i++)bit2[i] = -3e9;
for(int i = n - 1; i >= 0; i--){
int id = lower_bound(comp.begin(), comp.end(), p[i].se) - comp.begin() + 1;
ll res = get2(id);
if(res >= p[i].se + p[i].fi){
ok[i] = 1;
}
upd2(id, p[i].se + p[i].fi);
}
int ans = 0;
forr(i, 0, n){
ans += (!ok[i]);
}
cout << ans;
return(0);
}
