#include<bits/stdc++.h>
using namespace std;
#define task "a"
#define se second
#define fi first
#define ll long long
#define ii pair<ll, ll>
const long mxN = 5e5 + 7, inf = 1e9 + 7;
int n;
ii a[mxN];
bool cmp(ii u, ii v)
{
return u.fi < v.fi || (u.fi == v.fi && u.se > v.se);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
//freopen(task".INP", "r", stdin);
//freopen(task".OUT", "w", stdout);
cin >> n;
for (int i = 1; i <= n; i++)
{
cin >> a[i].fi >> a[i].se;
a[i].fi -= a[i].se;
a[i].se = a[i].fi + 2 * a[i].se;
}
sort(a + 1, a + n + 1, cmp);
int ans = 0, v = 0;
for (int i = 2; i <= n; i++)
{
if (a[i].se > v)
{
ans++;
v = a[i].se;
}
}
cout << ans;
}
