#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2")
#include <bits/stdc++.h>
using namespace std;
inline int readInt() {
int x = 0;
char ch = getchar();
while (ch < '0' || ch > '9')
ch = getchar_unlocked();
while (ch >= '0' && ch <= '9') {
x = (x << 3) + (x << 1) + ch - '0';
ch = getchar_unlocked();
}
return x;
}
struct Point {
int x, y;
Point() {}
bool protects(const Point &p) { return abs(x - p.x) <= y - p.y; }
bool is_protected_by(const Point &p) { return abs(p.x - x) <= p.y - y; }
};
int main() {
int N = readInt();
vector<Point> a(N);
for (int i = 0; i < N; i++) {
a[i].x = readInt();
a[i].y = readInt();
}
stack<Point> stk;
for (int i = 0; i < N; ++i) {
if (stk.empty()) {
stk.push(a[i]);
continue;
}
if (a[i].is_protected_by(stk.top())) {
continue;
}
while (!stk.empty() && a[i].protects(stk.top())) {
stk.pop();
}
stk.push(a[i]);
}
cout << stk.size() << "\n";
}
