#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif
const int N = 5e5 + 5, inf = 1e9;
int n;
int a[N], b[N];
set<array<int, 2>> A, B;
int get(const set<array<int, 2>> &st, int x) {
return (*prev(st.lower_bound(array<int, 2>{x + 1, -2 * inf})))[1];
}
void add(set<array<int, 2>> &st, array<int, 2> x) {
for (auto it = st.lower_bound(array<int, 2>{x[0]}); it != st.end(); it = st.erase(it)) {
if (x[1] < (*it)[1]) {
break;
}
}
st.insert(x);
}
int main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> a[i] >> b[i];
}
vector<int> ord(n); iota(ord.begin(), ord.end(), 1);
sort(ord.begin(), ord.end(), [&](int u, int v) {
return b[u] > b[v];
});
A.insert({0, -2 * inf}), B.insert({0, -2 * inf});
int res = 0;
for (int x : ord) {
if (get(A, a[x]) < a[x] + b[x] && get(B, inf - a[x] + 1) < b[x] - a[x]) {
++res;
add(A, {a[x], a[x] + b[x]});
add(B, {inf - a[x] + 1, b[x] - a[x]});
}
}
cout << res;
return 0;
}
