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
import collections
import math
import functools
import itertools
import bisect
import operator
import heapq
import random
true=True
false=False
null=None
SLOW=True
memoi=functools.lru_cache(None)
tcid=0
tcmax=99999999
def fast(): SLOW=False
def compute(val, func): return func(val)
def seq(lo,hi,step=1): 
 return range(lo,hi+1,step)
def sround(val,nd):
 return f'{val:.{nd}f}'
def ceil(a,b):
 ans=a//b
 if a%b!=0: ans+=1
 return ans
def perr(*args,**kwargs): 
 if SLOW:
  print(*args,file=sys.stderr,**kwargs)
def line():
 ln=sys.stdin.readline().strip()
 #perr(ln)
 if ln=='': sys.exit()
 return ln
def lines(n): return [line() for i in range(n)]
def split(ln=None): return (ln or line()).split()
def num(str=None):
 str=str or line()
 return float(str) if '.' in str else int(str)
def nums(o=None):
 if o is not None:
  if isinstance(o, int): o=lines(o)
  elif isinstance(o, str): o=split(o)
 return list(map(num, o or split()))
"""
ceil(a,b) sround(val,nd) true false null @memoi
num(?) nums(?) split(?) lines(n) line()
perr(print) tcmax seq() compute(v,f) tcid fast()
"""
#{#

#}#
def mainloop(tcid=1):
# {{{
 def solve():
  n=num()
  lft=[]
  rgt=[]
  hei=[]
  for ln in lines(n):
   x,h=nums(ln)
   lft.append(x)
   rgt.append(x)
   hei.append(h)
  if n<3:
   return n
  up=[true]*n
  up[0]=up[-1]=false
  for ii in range(1,n-1):
   if up[ii]:
    if lft[ii]-hei[ii]>rgt[ii-1]:
     up[ii]=false
     lft[ii]-=hei[ii]
    elif rgt[ii]+hei[ii]<lft[ii+1]:
     up[ii]=false
     rgt[ii]+=hei[ii]
  return up.count(false)
 ans=solve()
 print(ans)
# }}}
while tcid<tcmax:
 tcid+=1
 mainloop(tcid)
"""

"""