import java.io.*;
import java.util.*;
public class Main {
static class Building {
long A; // X - Y
long B; // X + Y
public Building(long A, long B) {
this.A = A;
this.B = B;
}
}
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
// Read the number of buildings.
int n = Integer.parseInt(br.readLine().trim());
Building[] buildings = new Building[n];
// Read building coordinates and compute A and B.
for (int i = 0; i < n; i++) {
String[] tokens = br.readLine().split(" ");
long X = Long.parseLong(tokens[0]);
long Y = Long.parseLong(tokens[1]);
buildings[i] = new Building(X - Y, X + Y);
}
// Sort buildings by B descending; if B's are equal, sort by A ascending.
Arrays.sort(buildings, new Comparator<Building>() {
@Override
public int compare(Building b1, Building b2) {
if (b1.B == b2.B)
return Long.compare(b1.A, b2.A);
return Long.compare(b2.B, b1.B);
}
});
// Greedy selection of buildings to plant lightning rods.
long bestA = Long.MAX_VALUE;
int ans = 0;
for (Building b : buildings) {
// If bestA is already less than or equal to the current building's A,
// it means this building is protected by an earlier chosen rod.
if (bestA <= b.A)
continue;
// Otherwise, plant a rod here and update bestA.
ans++;
bestA = b.A;
}
System.out.println(ans);
}
}
