#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#define rep(i, s, e) for (ll i = s; i < e; i++)
#define upmax(a, b) a = max(a, b)
#define upmin(a, b) a = min(a, b)
using namespace std;
using ll = int;
using vll = vector<ll>;
using vvll = vector<vll>;
using pll = pair<ll, ll>;
using vpll = vector<pll>;
void solve() {
ll n;
cin >> n;
vll x(n), y(n);
rep(i, 0, n) cin >> x[i] >> y[i];
vll arr(n);
vll arr2(n);
rep(i, 0, n) {
arr[i] = x[i] - y[i];
arr2[i] = x[i] + y[i];
}
vector<bool> ans(n, true);
ll mn = arr[n - 1];
for (ll i = n - 2; i >= 0; i--) {
if (arr[i] >= mn) {
ans[i] = false;
}
else mn = arr[i];
}
ll mx = arr2[0];
rep(i, 1, n) {
if (arr2[i] <= mx) {
ans[i] = false;
}
else mx = arr2[i];
}
ll res = 0;
rep(i, 0, n) if (ans[i]) res++;
cout << res << '\n';
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
solve();
}
