#include <algorithm>
#include <iostream>
using namespace std;
const int N = 500000;
const int INF = 0x3f3f3f3f;
int xx[N], ee[N], ii[N], pp[N], qq[N];
int main() {
ios_base::sync_with_stdio(false), cin.tie(NULL);
int n; cin >> n;
for (int i = 0; i < n; i++)
cin >> xx[i] >> ee[i], ii[i] = i;
sort(ii, ii + n, [] (int i, int j) { return xx[i] != xx[j] ? xx[i] < xx[j] : ee[i] < ee[j]; });
int n_ = 1;
for (int h = 1; h < n; h++) {
int i = ii[h], i_ = ii[n_ - 1];
if (xx[i] > xx[i_] || ee[i] > ee[i_])
ii[n_++] = i;
}
n = n_;
for (int p = -INF, h = 0; h < n; h++) {
int i = ii[h];
pp[h] = p, p = max(p, xx[i] + ee[i]);
}
for (int q = -INF, h = n - 1; h >= 0; h--) {
int i = ii[h];
qq[h] = q, q = max(q, ee[i] - xx[i]);
}
int ans = 0;
for (int h = 0; h < n; h++) {
int i = ii[h];
if (xx[i] + ee[i] > pp[h] && ee[i] - xx[i] > qq[h])
ans++;
}
cout << ans << '\n';
return 0;
}
