#pragma GCC target("avx2,bmi2")
#include <bits/stdc++.h>
using namespace std;
#ifndef ONLINE_JUDGE
#define getchar_unlocked() getchar()
#endif
inline int read() {
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;
}
int x[10000000], y[10000000];
const int inf = 1e9;
using T = pair<int, int>;
int main() {
int n = read();
for (int i = 0; i < n; i++) {
x[i] = read();
y[i] = read();
}
vector<pair<int, int>> ds(n);
for (int i = 0; i < n; i++) {
ds[i] = make_pair(x[i] - y[i], x[i] + y[i]);
}
sort(ds.begin(), ds.end(), [](const T& a, const T& b) {
if (a.first == b.first) {
return (a.second > b.second);
}
return (a.first < b.first);
});
int mx = -inf, ans = 0;
for (int i = 0; i < n; i++) {
if (mx < ds[i].second) {
ans++;
}
mx = max(mx, ds[i].second);
}
cout << ans << '\n';
}
