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.util.*;
import java.io.*;
import java.lang.*;
import java.lang.Math;

public class C{
	public static class tree implements Comparable<tree>{
		public int x,h;
		public tree(int tx,int th){
			this.x=tx; this.h=th;
		}
		@Override
		public int compareTo(tree T) {
			if (this.x==T.x)
				return 0;
			return (this.x-T.x);
		}
	};
	static tree []a;
	static int n,res;
	static int u[],v[];
	public static void main(String[] args)throws Exception{
		n=reader.nextInt(); a=new tree[n];
		if (n<=2){
			System.out.println(n);
			System.exit(0);
		}
		int i,j,L,R;
		for (i=0;i<n;i++)
			a[i]=new tree(reader.nextInt(),reader.nextInt());
		Arrays.sort(a);
		res=0;
		u=new int[n];		v=new int[n];
		for (i=0;i<n;i++){
			u[i]=a[i].x;
			v[i]=a[i].x;
//			System.out.println(a[i].x+" "+a[i].h);
		}
		
		L=Integer.MIN_VALUE;

	//	System.out.println(L);
		for (i=0;i<n;i++){
			if (L<(a[i].x - a[i].h)){
				res++;
				v[i]=a[i].x - a[i].h;
			}
			L=a[i].x;
		}
		R=Integer.MAX_VALUE;
		for (j=n-1;j>=0;j--){
			if ((a[j].h+a[j].x)<R){
				if (v[j]==u[j]) res++;
				v[j]=a[j].x;
			}
			R=Math.min(v[j],R);
		}
		System.out.print(res);
	}
	
	static class reader{
		static BufferedReader bReader=new BufferedReader(new InputStreamReader(System.in));
		static StringTokenizer token=new StringTokenizer("");
		static String readNextLine() throws Exception{
			return bReader.readLine();
		}
		static String next() throws Exception{
			while (token.hasMoreTokens()==false){
				token=new StringTokenizer(bReader.readLine());
			}
			return token.nextToken();
		}
		static int nextInt()throws Exception{
			while (token.hasMoreTokens()==false){
				token=new StringTokenizer(bReader.readLine());
			}
			return Integer.parseInt(token.nextToken());
		}
		static long nextLong()throws Exception{
			while (token.hasMoreTokens()==false){
				token=new StringTokenizer(bReader.readLine());
			}
			return Long.parseLong(token.nextToken());
		}
		static double nextDouble()throws Exception{
			while (token.hasMoreTokens()==false){
				token=new StringTokenizer(bReader.readLine());
			}
			return Double.parseDouble(token.nextToken());
		}
	}
}
