#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;
for (int i = 1; i <= n; i ++)
{
bool covered = false;
for (int j = 1; j < i; j ++)
{
if (abs(p[i].x - p[j].x) <= p[j].y - p[i].y)
{
covered = true;
break;
}
}
if (!covered)
ans ++;
}
cout << ans << endl;
}
int main()
{
solve();
return 0;
}
