#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 5e5+5;
int n;
vector<pair<ll,ll>> keep;
ll a[N], b[N];
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n;
for( int i=0;i<n;i++ )
{
ll x, e;
cin >> x >> e;
keep.push_back( {-x, e} );
}
sort( keep.begin(), keep.end() );
ll mx = -1e18;
for( int i=0;i<n;i++ )
{
auto [x, e] = keep[i];
a[i] = mx;
mx = max( mx, e+x );
}
mx = -1e18;
for( int i=n-1;i>=0;i-- )
{
auto [x, e] = keep[i];
b[i] = mx;
mx = max( mx, e-x );
}
int ans = 0;
for( int i=0;i<n;i++ )
{
auto [x, e] = keep[i];
if( a[i]>=e+x || b[i]>=e-x ) continue;
ans++;
}
cout << ans << "\n";
}
