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.awt.Point;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.PriorityQueue;
import java.util.StringTokenizer;

/**
 *
 * @author Mojtaba
 */
public class Main {

    public static void main(String[] args) throws IOException {
        MyScanner in = new MyScanner(System.in);
        //PrintWriter writer = new PrintWriter(new BufferedOutputStream(System.out));
        StringBuilder sb = new StringBuilder("");

        int n = in.nextInt();
        int[] x = new int[n];
        int[] h = new int[n];
        for (int i = 0; i < n; i++) {
            x[i] = in.nextInt();
            h[i] = in.nextInt();
        }
        int lastLeft = Integer.MIN_VALUE;
        int answer = n > 1 ? 2 : 1;
        for (int i = 1; i < n - 1; i++) {
            if (lastLeft < (x[i] - h[i]) && (x[i] - h[i]) > x[i - 1]) {
                lastLeft = x[i];
                answer++;
            } else if ((x[i] + h[i]) < x[i + 1]) {
                answer++;
                lastLeft = x[i] + h[i];
            }
        }
        sb.append(answer);

        //writer.println(sb.toString().trim());
        //writer.flush();
        //writer.close();
        System.out.println(sb.toString().trim());
        in.close();
    }
}

class MyScanner {

    BufferedReader reader;
    StringTokenizer tokenizer;

    public MyScanner(InputStream stream) {
        this.reader = new BufferedReader(new InputStreamReader(stream));
    }

    public int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    public int[] nextIntegerArray(int n) throws IOException {
        int[] a = new int[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = nextInt();
        }
        return a;
    }

    public long[] nextLongArray(int n) throws IOException {
        long[] a = new long[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = nextLong();
        }
        return a;
    }

    public int nextInt(int radix) throws IOException {
        return Integer.parseInt(next(), radix);
    }

    public long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    public long nextLong(int radix) throws IOException {
        return Long.parseLong(next(), radix);
    }

    public double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }

    public BigInteger nextBigInteger() throws IOException {
        return new BigInteger(next());
    }

    public BigInteger nextBigInteger(int radix) throws IOException {
        return new BigInteger(next(), radix);
    }

    public String next() throws IOException {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
            return this.next();
        }
        return tokenizer.nextToken();
    }

    public void close() throws IOException {
        this.reader.close();
    }
}