#include <bits/stdc++.h>
using namespace std;
#define sz(x) int(x.size())
#define all(x) begin(x),end(x)
using ii = pair<int, int>;
const int MAX_N = 5e5;
const int INF = 1e9 + 20;
ii st[2 * MAX_N];
int n;
const ii NEUTR = {INF, -INF};
inline ii op(ii lhs, ii rhs) {
return {min(lhs.first, rhs.first), max(lhs.second, rhs.second)};
}
void init() {
for (int i = 0; i < 2 * n; i++) st[i] = NEUTR;
}
void update(int p, ii v) {
st[p += n] = v;
while (p /= 2) st[p] = op(st[2 * p], st[2 * p + 1]);
}
ii query(int l, int r) {
ii res = NEUTR;
for (l += n, r += n; l < r; l /= 2, r /= 2) {
if (l & 1) res = op(res, st[l++]);
if (r & 1) res = op(st[--r], res);
}
return res;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n;
vector<int> x(n), e(n);
for (int i = 0; i < n; i++) {
cin >> x[i] >> e[i];
}
vector<int> vals = x;
sort(all(vals));
vals.erase(unique(all(vals)), end(vals));
const auto pos = [&](int v) {
return int(lower_bound(all(vals), v) - begin(vals));
};
vector<int> id(n);
iota(all(id), 0);
sort(all(id), [&](const int &lhs, const int &rhs) {
return e[lhs] > e[rhs];
});
init();
int ans = 0;
for (int i = 0; i < n; i++) {
int p = pos(x[id[i]]);
int mini = query(p, sz(vals)).first;
int maxi = query(0, p).second;
int diff = x[id[i]] - e[id[i]];
int sum = x[id[i]] + e[id[i]];
if (mini > diff && maxi < sum) ans++;
update(p, ii{diff, sum});
}
cout << ans << '\n';
return 0;
}
