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.*;
import java.util.*;
import java.io.IOException;
import java.io.InputStream;


public class Main {
    public static void main(String[] args) {

        File file = new File("in.txt");
        File fileOut = new File("out.txt");
        InputStream inputStream = null;
        OutputStream outputStream = null;
//         try {inputStream= new FileInputStream(file);} catch (FileNotFoundException ex){return;};
//        try {outputStream= new FileOutputStream(fileOut);} catch (FileNotFoundException ex){return;};
        inputStream = System.in;
        outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        solver.solve(1, in, out);
        out.close();
    }


}

class Task {

    public void solve(int testNumber, InputReader in, PrintWriter out) {
		long n = in.nextLong();
		long cut_trees = 0;
		long biggest_occ_space = Long.MIN_VALUE;
		long old_tree_pos = 0;
		long old_tree_len = 0;
		for(long i = 0 ; i <= n ;i++){
			long tree_pos;
			long tree_len;
			if(i != n){
				tree_pos = in.nextLong();
				tree_len = in.nextLong();
			}else{
				tree_pos = Long.MAX_VALUE;
				tree_len = 0;
			}
			
			if(i == 0){
				old_tree_pos = tree_pos;
				old_tree_len = tree_len;
				continue;
			}
			
			//Always fell the first tree left
			//if(i == 0){
				//System.out.println("Tree fel to left ["+(tree_pos - tree_len)+";"+tree_pos+"]");
				//biggest_occ_space = tree_pos;
				//cut_trees++;
				//continue;
			//}
			
			//First check if it can fell to the left
			if(old_tree_pos - old_tree_len > biggest_occ_space){
				//System.out.println("Tree fel to left ["+(old_tree_pos - old_tree_len)+";"+old_tree_pos+"]");
				biggest_occ_space = old_tree_pos;
				cut_trees++;
			}else if(old_tree_pos+old_tree_len < tree_pos){
				//Drop it to the right
				//System.out.println("Tree fel to right ["+old_tree_pos+";"+(old_tree_pos+old_tree_len)+"]");
				biggest_occ_space = old_tree_pos+old_tree_len;
				cut_trees++;
			}else{
				//System.out.println("No space to drop tree");
				biggest_occ_space = old_tree_pos;
			}
			
			old_tree_pos = tree_pos;
			old_tree_len = tree_len;
		}
		
		out.println(cut_trees);
	}
}

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 String nextLine(){
        try {
            return reader.readLine();
        } catch (IOException e){
            throw new RuntimeException(e);
        }
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }
    public long nextLong() { return Long.parseLong(next()); }

}