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.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;

/**
 *
 */
public class TaskC {
    public static void main(String[] args) {
        InputStream inputStream;
        String str = null;
        if(str == null){
            inputStream = System.in;
        }else{
            inputStream = new ByteArrayInputStream(str.getBytes());
        }
        
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Solver solver = new Solver();
        solver.solve(1, in, out);
        out.close();
    }
    

    static class Solver {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int numTrees = in.nextInt();
            
            Tree[] trees = new Tree[numTrees];
            
            for(int i=0;i<numTrees;i++){
                trees[i] = new Tree(in.nextInt(), in.nextInt());
            }
            
            int count = Math.min(numTrees, 2);
            trees[0].left = trees[0].right-trees[0].height;
            trees[numTrees-1].right = trees[numTrees-1].right+trees[numTrees-1].height;
            
            //Looking at the spaces in-between
            for(int tree=1;tree<numTrees-1;tree++){
                int treeFallLeft = trees[tree].left - trees[tree].height;
                int treeFallRight = trees[tree].right + trees[tree].height;
                
                //Try to fall left (if you can, do so)
                if(treeFallLeft > trees[tree-1].right){
                    trees[tree].left = trees[tree].right-trees[tree].height;
                    count++;
                }else if(treeFallRight < trees[tree+1].left){
                    //Try to fall right (if you can, do so)
                    trees[tree].right = trees[tree].left + trees[tree].height;
                    count++;
                }else{
                    //Do nothing - don't fall!
                }
            }
            
            System.out.println(count);
        }
    }
    
    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;
 
        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }
 
        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }
 
        public int nextInt() {
            return Integer.parseInt(next());
        }
    }
}

class Tree{
    int height;
    int left;
    int right;
    
    public Tree(int loc, int height){
        this.height = height;
        this.left = loc;
        this.right = loc;
    }
}