#include <bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#define int long long
#define pii pair<int,int>
#define vi vector<int>
#define ff first
#define ss second
#define sp << " " <<
#define all(x) x.begin(),x.end()
#define big(x) ((int)(x.size()))
using namespace std;
const int MOD = 1e9+7, LIM = 1e6+1, inf = 2e18;
const int N = 1e5+1;
void solve() {
int n;
cin >> n;
//benden <= olanlarda max x+e
//benden >= olanlarda min e-x
vector<pii> ppl(n);
for (int i = 0;i<n;i++) cin >> ppl[i].ff >> ppl[i].ss;
sort(all(ppl));
ppl.erase(unique(all(ppl)),ppl.end());
n = big(ppl);
int mx = -inf,mn = inf;
vi cont(n,0);
for (int i = 0;i<n;i++) {
if (mx >= ppl[i].ff+ppl[i].ss) cont[i] = 1;
mx = max(mx,ppl[i].ff+ppl[i].ss);
}
for (int i = n-1;i>=0;i--) {
if (mn <= ppl[i].ff-ppl[i].ss) cont[i] = 1;
mn = min(mn,ppl[i].ff-ppl[i].ss);
}
cout << n-count(all(cont),1) << '\n';
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef Dodi
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif
int t = 1;
//cin >> t;
while (t --> 0) solve();
}
