4
10 4
15 1
19 3
20 1
 2
1 999999999
1000000000 1000000000
 67
1 1
3 8
4 10
7 8
9 2
10 1
11 5
12 8
13 4
16 6
18 3
19 3
22 5
24 6
27 5
28 3
29 3
30 5
32 5
33 10
34 7
35 8
36 5
41 3
42 2
43 5
46 4
48 4
49 9
52 4
53 9
55 1
56 4
59 7
68 7
69 4
71 9
72 10
74 5
76 4
77 9
80 7
81 9
82 5
83 5
84 9
85 7
86 9
87 4
88 7
89 10
90 3
91 5
92 10
93 5
94 8
95 4
96 2
97 10
98 1
99 3
100 1
101 5
102 4
103 8
104 8
105 8
 10
999999900 1000000000
999999901 1000000000
999999902 1000000000
999999903 1000000000
999999904 1000000000
999999905 1000000000
999999906 1000000000
999999907 1000000000
999999908 1000000000
999999909 1000000000
 35
1 7
3 11
6 12
7 6
8 5
9 11
15 3
16 10
22 2
23 3
25 7
27 3
34 5
35 10
37 3
39 4
40 5
41 1
44 1
47 7
48 11
50 6
52 5
57 2
58 7
60 4
62 1
67 3
68 12
69 8
70 1
71 5
72 5
73 6
74 4
 1
1000000000 1000000000
 2
100000000 1000000000
1000000000 1000000000
 10
7 12
10 2
12 2
15 1
19 2
20 1
53 25
63 10
75 12
87 1
 3
1 1
1000 1000
1000000000 1000000000
 40
1 1
2 1
3 1
4 1
5 1
6 1
7 1
8 1
9 1
10 1
11 1
12 1
13 1
14 1
15 1
16 1
17 1
18 1
19 1
20 1
21 1
22 1
23 1
24 1
25 1
26 1
27 1
28 1
29 1
30 1
31 1
32 1
33 1
34 1
35 1
36 1
37 1
38 1
39 1
40 1

4
 2
 5
 2
 10
 1
 2
 9
 3
 2

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();

            TaskC.Tree[] tree = new TaskC.Tree[n];

            for (int i = 0; i < n; ++i) {
                int x = in.nextInt();
                int h = in.nextInt();
                tree[i] = new TaskC.Tree(x, h);
            }

            int res = 0;
            for (int i = 0; i < n; ++i) {
                int x = tree[i].x;
                int h = tree[i].h;

                if (i == 0 || i == n - 1) {
                    ++res;
                    continue;
                }

                if (cutTree(i, x, x - h, tree)) {
                    ++res;
                    continue;
                }

                if (cutTree(i, x, x + h, tree)) {
                    ++res;
                    continue;
                }
            }

            out.print(res);
        }

        private boolean cutTree(int p, int from, int to, TaskC.Tree[] distance) {

            if (from < to) {
                for (int i = p + 1; i < distance.length; ++i) {
                    if (distance[i].x <= to || (distance[i].left != 0 && distance[i].left <= to)) return false;
                    else {
                        distance[p].right = to;
                        break;
                    }
                }
                return true;

            } else {
                for (int i = p - 1; i >= 0; --i) {
                    if (distance[i].x >= to || (distance[i].right != 0 && distance[i].right >= to)) return false;
                    else {
                        distance[p].left = to;
                        break;
                    }
                }
                return true;
            }
        }

        static class Tree {
            public int x;
            public int h;
            public int left = 0;
            public int right = 0;

            public Tree(int x, int h) {
                this.x = x;
                this.h = h;
            }

        }

    }
}

