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

from collections import deque
import sys

class Tree:
    def __init__(self, pos, height):
        self.pos = pos;
        self.height = height;

line = input().split(" ");
test_cases = int(line[0]);

trees_lr = deque([]);

for tc in range(test_cases):
    line = input().split(" ");
    trees_lr.append(Tree(int(line[0]), int(line[1])));

if(len(trees_lr) == 1):
    sys.stdout.write(str(1));
else:
    lb = trees_lr.popleft().pos;
    ub = trees_lr.pop().pos;
    #print("lb: " + str(lb) + " ub: " + str(ub));
    count = 2;
    is_left = True;
    while(trees_lr):
        #print(len(trees_lr));
        #print(is_left);
        if(is_left):
            cur_tree = trees_lr.popleft();
            if(cur_tree.pos - cur_tree.height > lb):
                count += 1;
                #print("New count: " + str(count));
                lb = cur_tree.pos;
            else:
                if(trees_lr):
                    next_tree = trees_lr.popleft();
                    next_pos = next_tree.pos;
                    trees_lr.appendleft(next_tree);
                else:
                    next_pos = ub;
                if(cur_tree.pos + cur_tree.height < next_pos):
                    count += 1;
                    lb = cur_tree.pos + cur_tree.height;
                    #print("New count: " + str(count));
                else:
                    lb = cur_tree.pos;
            is_left = False;
        else:
            cur_tree =  trees_lr.pop();
            if(cur_tree.pos + cur_tree.height < ub):
                count += 1;
                #print("New count: " + str(count));
                ub = cur_tree.pos;
            else:
                if(trees_lr):
                    next_tree = trees_lr.pop();
                    next_pos = next_tree.pos;
                    trees_lr.append(next_tree);
                else:
                    next_pos = lb;
                if(cur_tree.pos - cur_tree.height > next_pos):
                    count += 1;
                    ub = cur_tree.pos - cur_tree.height;
                    #print("New count: " + str(count));
                else:
                    ub = cur_tree.pos;
            is_left = True;
        #print("lb: " + str(lb) + " ub: " + str(ub));
    #print()
    sys.stdout.write(str(count));