#include <bits/stdc++.h>
using namespace std;
using ll=int64_t;
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define _F(i,a,b,s) for(int i=(a);((s)>0?i<(b):i>(b));i+=(s))
#define _1(e) _F(i,0,e,1)
#define _2(i,e) _F(i,0,e,1)
#define _3(i,b,e) _F(i,b,e,(b)<(e)?1:-1)
#define _G(a,b,c,d,e,...) e
#define FOR(...) _G(__VA_ARGS__,_F,_3,_2,_1)(__VA_ARGS__)
int main() {
ios::sync_with_stdio(0),cin.tie(0);
int n; cin >> n;
stack<pair<int, int>> ans;
FOR (n) {
int x, y; cin >> x >> y;
pair<int, int> top;
while (!ans.empty()) {
top = ans.top();
if (abs(x - top.first) <= y - top.second) {
ans.pop();
} else {
break;
}
}
if (ans.empty() || abs(top.first - x) > top.second - y) ans.push({x, y});
}
cout << ans.size() << '\n';
}
