import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.*;
public class Main {
public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int n = Integer.parseInt(br.readLine());
int[][]reach = new int[n+1][3];
int[][]influence = new int[n+1][3];
for (int i = 1; i <= n; i++) {
StringTokenizer st = new StringTokenizer(br.readLine());
int x = Integer.parseInt(st.nextToken());
int e = Integer.parseInt(st.nextToken());
reach[i][0] = x;
reach[i][1] = x + e;
reach[i][2] = i;
influence[i][0] = x;
influence[i][1] = x - e;
influence[i][2] = i;
}
Arrays.sort(reach, 1, n + 1, (X, Y) -> {
if (X[0] != Y[0]) return Integer.compare(X[0], Y[0]);
if (X[1] != Y[1]) return Integer.compare(Y[1], X[1]);
return Integer.compare(X[2], Y[2]);
});
Arrays.sort(influence, 1, n + 1, (X, Y) -> {
if (X[0] != Y[0]) return Integer.compare(X[0], Y[0]);
if (X[1] != Y[1]) return Integer.compare(Y[1], X[1]);
return Integer.compare(X[2], Y[2]);
});
List<Integer> list_reach = new ArrayList<>();
List<Integer> list_influence = new ArrayList<>();
for (int i = n; i >= 1; i--) {
if (list_reach.isEmpty() || reach[i][1] != reach[list_reach.get(list_reach.size() - 1)][1] || reach[i][0] != reach[list_reach.get(list_reach.size() - 1)][0]) {
while (!list_reach.isEmpty()) {
int back = list_reach.get(list_reach.size() - 1);
if (reach[i][1] >= reach[back][1] || (reach[i][1] == reach[back][1] && reach[i][0] != reach[back][0])) {
list_reach.remove(list_reach.size() - 1);
} else {
break;
}
}
list_reach.add(i);
}
}
Collections.reverse(list_reach);
for (int i = 1; i <= n; i++) {
while (!list_influence.isEmpty() && influence[i][1] <= influence[list_influence.get(list_influence.size() - 1)][1]) {
list_influence.remove(list_influence.size() - 1);
}
list_influence.add(i);
}
int ans = 0, i = 0, j = 0;
while (i < list_reach.size() && j < list_influence.size()) {
int i1 = list_reach.get(i), i2 = list_influence.get(j);
if (reach[i1][0] < influence[i2][0]) {
i++;
} else if (reach[i1][0] > influence[i2][0]) {
j++;
} else {
if (reach[i1][2] == influence[i2][2]) ans++;
i++;
j++;
}
}
System.out.println(ans);
}
}
