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.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Fences {

	public static class Interval implements Comparable<Interval> {

		public int left, right;

		public Interval(int l, int r) {
			this.left = l;
			this.right = r;
		}

		public boolean intersect(Interval other) {
			Interval ml, mr;
			if (this.left == other.left) {
				return true;
			}
			if (this.left < other.left) {
				ml = this;
				mr = other;
			} else {
				ml = other;
				mr = this;
			}
			return (ml.right >= mr.left);
		}

		@Override
		public int compareTo(Interval other) {
			return this.left - other.left;
		}

		public boolean equals(Object value) {
			Interval other = (Interval) value;
			return this.intersect(other);
		}

	}
	
	public static class Tree implements Comparable<Tree> {
		
		public int x, height;

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

		@Override
		public int compareTo(Tree other) {
			return x - other.x;
		}
		
		public Interval cutLeft() {
			return new Interval(this.x - this.height, this.x);
		}
		
		public Interval cutRight() {
			return new Interval(this.x, this.x + this.height);
		}		
		
	}

	public static int maxNumberOfCuts(Tree[] trees) {

		Arrays.sort(trees);
		
		int nFallenTrees = 1;
	
		Interval prevPoint = new Interval(trees[0].x, trees[0].x);
		
		for (int i = 1; i < trees.length - 1; ++ i) {
		
			Interval currentPoint = new Interval(trees[i].x, trees[i].x);
			Interval nextPoint = new Interval(trees[i + 1].x, trees[i + 1].x);									
			
			// Cut the tree and fall to left
			Interval iLeft = trees[i].cutLeft();					
			if (!prevPoint.intersect(iLeft)) {
				nFallenTrees += 1;
				prevPoint = iLeft; 
				continue;
			}
			
			// Cut the tree and fall to right
			Interval iRight = trees[i].cutRight();			
			if (!nextPoint.intersect(iRight)) {
				nFallenTrees += 1;
				prevPoint = iRight;
				continue;
			}			
			
			prevPoint = currentPoint;

		}
		
		if (trees.length > 1) {
			nFallenTrees += 1;	
		}				
		
		return nFallenTrees;

	}

	public static void main(String[] args) throws IOException {

		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		
		int n = Integer.parseInt(in.readLine());
		
		Tree[] trees = new Tree[n];
		for (int i = 0; i < n; i++) {
			StringTokenizer st = new StringTokenizer(in.readLine());
			trees[i] = new Tree(Integer.parseInt(st.nextToken()), Integer.parseInt(st.nextToken()));			
		}
		
		System.out.println(maxNumberOfCuts(trees));
		
	}

}
