/*
Author: Nguyen Chi Thanh - High School for the Gifted - VNU.HCM (i2528)
*/
#include <bits/stdc++.h>
using namespace std;
// #define int long long
#define ull unsigned long long
#define ld long double
#define pii pair<int, int>
#define fi first
#define se second
#define __builtin_popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) ((1ll << (x)))
#define debug(a, l, r) for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';
int n;
inline void input(int & x) {
x = 0;
char ch = getchar_unlocked();
while (ch < '0' || ch > '9') ch = getchar_unlocked();
while (ch >= '0' && ch <= '9') {
x = (x << 3) + (x << 1) + (ch & 15);
ch = getchar_unlocked();
}
}
inline void solve() {
cin >> n;
vector<pii> st;
for (int i = 1; i <= n; ++i) {
int x, y;
input(x);
input(y);
pii p = {x + y, x - y};
bool need = 1;
while (!st.empty()) {
int _x = st.back().fi, _y = st.back().se;
if (p.fi <= _x && p.se >= _y) {
need = 0;
break;
}
if (_x <= p.fi && _y >= p.se) st.pop_back();
else break;
}
if (need) st.push_back(p);
}
cout << (int)st.size();
}
signed main() {
#ifdef NCTHANH
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
// ios_base::sync_with_stdio(0);
// cin.tie(nullptr); cout.tie(nullptr);
solve();
return 0;
}
