// Starcraft 2 enjoyer //
#include <bits/stdc++.h>
// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
using namespace std;
#define LSOne(X) ((X) & -(X))
#define int long long
const int N = 5e5 + 5;
const int M = 15e5;
const int B = 18;
const long long K = 2;
const int LG = 60;
const long long INF = 1e18 + 5;
const int C = 26;
const int MOD = 1e9 + 7;
struct LazySegmentTree
{
vector<int> st, a, lazy;
int n;
void prop(int v, int l, int r)
{
st[v] = max(st[v], lazy[v]);
if (l != r)
{
lazy[2 * v] = max(lazy[2 * v], lazy[v]);
lazy[2 * v + 1] = max(lazy[2 * v + 1], lazy[v]);
}
lazy[v] = -INF;
}
void update(int v, int val, int l, int r, int tl, int tr)
{
prop(v, l, r);
if (tl > tr)
return;
if (tl <= l && r <= tr)
{
lazy[v] = max(lazy[v], val);
prop(v, l, r);
}
else
{
int m = (l + r) / 2;
update(2 * v, val, l, m, tl, min(tr, m));
update(2 * v + 1, val, m + 1, r, max(tl, m + 1), tr);
st[v] = max(st[2 * v], st[2 * v + 1]);
}
}
int get(int v, int l, int r, int tl, int tr)
{
prop(v, l, r);
if (tl > tr)
return -INF;
if (tl <= l && r <= tr)
{
return st[v];
}
else
{
int m = (l + r) / 2;
return max(get(2 * v, l, m, tl, min(tr, m)), get(2 * v + 1, m + 1, r, max(tl, m + 1), tr));
}
}
LazySegmentTree(int len)
{
n = len;
st.assign(4 * n, -INF);
lazy.assign(4 * n, -INF);
}
void update(int val, int l, int r)
{
update(1, val, 0, n - 1, l, r);
}
int get(int l, int r)
{
return get(1, 0, n - 1, l, r);
}
};
int n, ans;
pair<int, int> people[N];
vector<int> v;
bool cmp(pair<int, int> a, pair<int, int> b)
{
return a.second > b.second;
}
inline void solve()
{
cin >> n;
for (int x = 0; x < n; x++)
{
cin >> people[x].first >> people[x].second;
v.push_back(people[x].first);
}
sort(v.begin(), v.end());
v.erase(unique(v.begin(), v.end()), v.end());
sort(people, people + n, cmp);
LazySegmentTree le(n), ri(n);
ans = 0;
for (int x = 0; x < n; x++)
{
auto [i, j] = people[x];
int p = lower_bound(v.begin(), v.end(), i) - v.begin();
if (le.get(0, p) < i + j && ri.get(p, n - 1) < j - i)
{
// cout << i << " " << j << "\n";
ans++;
le.update(i + j, p, p);
ri.update(j - i, p, p);
}
}
cout << ans;
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
for (int x = 1; x <= t; x++)
{
solve();
}
return 0;
}
