#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
typedef long long ll;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
const int maxn = 5e5 + 10;
struct point
{
int x, y;
} p[maxn];
bool cmp(const point &p1, const point &p2)
{
return p1.y > p2.y;
}
int n;
void solve()
{
cin >> n;
for (int i = 1; i <= n; i ++)
{
cin >> p[i].x >> p[i].y;
}
sort(p + 1, p + n + 1, cmp);
int ans = 0;
set < pair < int, int > > st;
for (int i = 1; i <= n; i ++)
{
pair < int, int > cur = {p[i].x, i};
st.insert(cur);
set < pair < int, int > > :: iterator it = st.find(cur), hp;
bool covered = false;
if (it != st.begin())
{
hp = prev(it);
if (cur.first - hp -> first <= p[hp -> second].y - p[cur.second].y)
covered = true;
}
if (next(it) != st.end())
{
hp = next(it);
if (hp -> first - cur.first <= p[hp -> second].y - p[cur.second].y)
covered = true;
}
if (!covered)
ans ++;
else
st.erase(it);
}
cout << ans << endl;
}
int main()
{
solve();
return 0;
}
