#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int maxN = 5e5 + 5;
int id[maxN],a[maxN],b[maxN],n;
vector<int> v;
struct Tsegment_tree
{
    ll st[2 * maxN];
    void build()
    {
        for (int i = 0;i <= 2 * n;++i) st[i] = 1e18;
    }
    void update(int i,ll val)
    {
        for (st[i += n] = min(st[i],val);i > 1;i >>= 1)
            st[i >> 1] = min(st[i],st[i ^ 1]);
    }
    ll get(int l,int r)
    {
        ++r;
        ll res = 1e18;
        for (l += n,r += n;l < r;l >>= 1,r >>= 1)
        {
            if (l & 1) res = min(res,st[l++]);
            if (r & 1) res = min(res,st[--r]);
        }
        return res;
    }
    void build1()
    {
        for (int i = 0;i <= 2 * n;++i) st[i] = -1e18;
    }
    void update1(int i,ll val)
    {
        for (st[i += n] = max(st[i],val);i > 1;i >>= 1)
            st[i >> 1] = max(st[i],st[i ^ 1]);
    }
    ll get1(int l,int r)
    {
        ++r;
        ll res = -1e18;
        for (l += n,r += n;l < r;l >>= 1,r >>= 1)
        {
            if (l & 1) res = max(res,st[l++]);
            if (r & 1) res = max(res,st[--r]);
        }
        return res;
    }
}
s1,s2;
bool cmp(int x,int y)
{
    return b[x] > b[y];
}
void input()
{
    cin >> n;
    for (int i = 1;i <= n;++i)
    {
        cin >> a[i] >> b[i];
        id[i] = i;
        v.push_back(a[i]);
    }
    sort(v.begin(),v.end());
    v.erase(unique(v.begin(),v.end()),v.end());
}
int getid(int x)
{
    return lower_bound(v.begin(),v.end(),x) - v.begin() + 1;
}
void solve()
{
    sort(id + 1,id + n + 1,cmp);
    s1.build();
    s2.build1();
    //s1.update(2,b[8] - a[8]);
    //cout << s1.get(1,9) << "\n";
    int res = 0;
    for (int i = 1;i <= n;++i)
    {
        int x = id[i];
        int idx = getid(a[x]);
        //cout << idx << " " << s1.get(1,idx) << " " << s2.get1(idx,n) << " " << x << "\n";
        if (s1.get(idx,n) <= a[x] - b[x] || s2.get1(1,idx) >= a[x] + b[x]) continue;
        ++res;
        //cerr << x << "\n";
        s1.update(idx,a[x] - b[x]);
        s2.update1(idx,b[x] + a[x]);

    }
    cout << res;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
//    freopen("B.inp","r",stdin);
//    freopen("B.out","w",stdout);
    input();
    solve();
}