#include <bits/stdc++.h>
using namespace std;
//#define int long long
#define ll long long
#define rep(i,a,b) for (int i = a; i <= b; i++)
#define per(i,a,b) for (int i = a; i >= b; i--)
#define fi first
#define se second
#define pii pair<int,int>
#define pb push_back
const int MAXN = 5e5+10;
pii a[MAXN];
bool ok[MAXN];
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(nullptr);
int n;cin >> n;
rep(i,1,n) cin >> a[i].fi >> a[i].se, ok[i] = 1;
sort(a+1,a+n+1);
n = unique(a+1,a+n+1)-a-1;
set<int> st;
rep(i,1,n) {
int k = (a[i].fi + a[i].se);
auto it = st.lower_bound(k);
ok[i] &= (it == st.end());
st.insert(k);
}
st.clear();
per(i,n,1) {
int k = (a[i].se-a[i].fi);
auto it = st.lower_bound(k);
ok[i] &= (it == st.end());
st.insert(k);
}
int ans = 0;
rep(i,1,n) {
ans+=ok[i];
}
cout << ans << '\n';
return 0;
}
