#include <bits/extc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#define int long long
#define f first
#define s second
#define all(x) x.begin(), x.end()
#define debug(x) do{auto y = x; cout << #x << " = " << y << endl;}while(0)
// #define endl "\n"
#define unordered_map __gnu_pbds::gp_hash_table
using pii = pair<int, int>;
const int inf = 1ll << 60;
const int MOD = 1e9 + 7;
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n; cin >> n;
vector<pii> pts(n);
for(int i = 0; i < n; i++) {
int x, y; cin >> x >> y;
pts[i] = {x, y};
}
vector<pii> stac;
for(auto p : pts) {
#define sb stac.back()
while(stac.size() && p.s - p.f >= sb.s - sb.f) {
stac.pop_back();
}
if(!stac.size() || p.f + p.s > sb.f + sb.s) {
stac.push_back(p);
}
}
cout << stac.size() << endl;
}
