#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define ull unsigned long long
#define pii pair<int,int>
#define pll pair<long long, long long>
#define fi first
#define se second
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define lwb lower_bound
#define upb upper_bound
#define TASKNAME "NAME"
void init()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
///freopen(TASKNAME".INP","r",stdin); freopen(TASKNAME".OUT","w",stdout);
}
const int SZ = 1e7+5;
const ll INF = INT_MAX / 2, MOD = 1e9+7, INFLL = 2e18;
const double epsilon = 1e-3;
int n;
pii a[SZ];
vector<int> vec;
bool check(int i, int j)
{
return abs(a[i].fi - a[j].fi) <= a[i].se - a[j].se;
}
int main()
{
init();
cin >> n;
for(int i = 1; i <= n; i++)
{
cin >> a[i].fi >> a[i].se;
if(!vec.empty() && check(vec.back(), i)) continue;
while(!vec.empty() && check(i, vec.back())) vec.pop_back();
vec.pb(i);
}
cout << vec.size();
}
