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 sys

def solve():
    n_trees = int(sys.stdin.readline())
    if n_trees == 1:
        sys.stdin.readline()
        print 1
    elif n_trees == 2:
        sys.stdin.readline()
        sys.stdin.readline()
        print 2
    else:
        [f_tree, f_height] = [int(x) for x in sys.stdin.readline().split()]
        [s_tree, s_height] = [int(x) for x in sys.stdin.readline().split()]

        # start with 2 because f_tree always can fell left, 
        # and r_tree can always fell right.
        ctr = 1
        left = True
        for x in range(n_trees-2):
            [t_tree, t_height] = [int(y) for y in sys.stdin.readline().split()]
            int_1 = s_tree - s_height
            int_2 = s_tree + s_height
            if left == True:
                if int_1 > f_tree:
                    ctr += 1
                elif int_2 < t_tree:
                        ctr += 1
                        left = False
                else:
                    left = True
            else:
                if int_1 > f_tree + f_height:
                    ctr += 1
                    left = True
                elif int_2 < t_tree:
                    ctr += 1
                    left = False
                else:
                    left = True
            f_tree = s_tree
            f_height = s_height
            s_tree = t_tree
            s_height = t_height

        # fell last tree to right side
        ctr += 1
        print ctr

solve()
