Problem:
Score : 200 points

Problem Statement

In a factory, there are N robots placed on a number line.
Robot i is placed at coordinate X_i and can extend its arms of length L_i in both directions, positive and negative.

We want to remove zero or more robots so that the movable ranges of arms of no two remaining robots intersect.
Here, for each i (1 \leq i \leq N), the movable range of arms of Robot i is the part of the number line between the coordinates X_i - L_i and X_i + L_i, excluding the endpoints.

Find the maximum number of robots that we can keep.

Constraints

1 \leq N \leq 100,000

0 \leq X_i \leq 10^9 (1 \leq i \leq N)

1 \leq L_i \leq 10^9 (1 \leq i \leq N)

If i \neq j, X_i \neq X_j.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
X_1 L_1
X_2 L_2
\vdots
X_N L_N

Output

Print the maximum number of robots that we can keep.

Sample Input 1

4
2 4
4 3
9 3
100 5

Sample Output 1

3

By removing Robot 2, we can keep the other three robots.

Sample Input 2

2
8 20
1 10

Sample Output 2

1

Sample Input 3

5
10 1
2 1
4 1
6 1
8 1

Sample Output 3

5

Solution in PyPy3 (2.4.0) (judge verdict: Wrong Answer)

'''
条件に合うものを絞り込む
data = [1, 2, 3]
s = [x for x in data if x % 3 == 0]
'''
'''
文字配列を数値に
l_si = ['-10', '0', '100']

l_si_i = [int(s) for s in l_si]
'''
'''
a = [2, 4, 6, 8]
b = [3, 6, 9]

print(list(set(a) | set(b)))  # 和集合
print(list(set(a) & set(b)))  # 積集合
'''
'''
N = int(stdin.readline().rstrip())
A = [int(x) for x in stdin.readline().rstrip().split()]
count = 0
while len([x for x in A if x % 2 == 0]) == N:
    A = list(map(lambda y: y / 2, A))
    count += 1
print(count)
'''
'''
.append(要素)
.extend(要素)
.insert(場所,要素)
del 配列名[場所]
-1で末尾で末尾から一つ前
'''
'''
間に空白追加
' '.join(lis)
'''
'''
copy.copy(配列名)
'''
'''
sort()
sorted(reverse=true)
'''
'''
2分探索
bisect.bisect_left(リスト, 要素)
'''
'''
リスト同士の演算
list(map(lambda x, y: x+y, el2, el3))
'''
'''
配列の初期化
配列名=[a]*n+[b]*m
'''
'''
重複
list(set())
２次元配列
list(map(list, set(map(tuple, addition))))
'''
'''
順列
for el in itertools.permutations(配列のパターン):
'''
'''
Decimal()
'''
# 入力 =stdin.readline().rstrip()
# 分割 = stdin.readline().rstrip().split()




from sys import stdin
from itertools import accumulate, dropwhile, takewhile, groupby
import bisect
import copy
import math
import itertools
from functools import reduce
from operator import mul
def gcd(*numbers):
    return reduce(math.gcd, numbers)


def gcd_list(numbers):
    return reduce(math.gcd, numbers)


def lcm_base(x, y):
    return (x * y) // math.gcd(x, y)


def lcm(*numbers):
    return reduce(lcm_base, numbers, 1)


def lcm_list(numbers):
    return reduce(lcm_base, numbers, 1)


N = int(stdin.readline().rstrip())
Xs = []
Ls = []
Ran = []
for k in range(N):
    tmp = stdin.readline().rstrip().split()
    Xs.append(int(tmp[0]))
    Ls.append(int(tmp[1]))
    before = int(tmp[0]) - int(tmp[1])
    after = int(tmp[0]) + int(tmp[1])
    Ran.append([before, after, int(tmp[0])])
sorted_data = sorted(Ran, key=lambda x: (x[2]))
Ran = sorted_data
count = 0
posAfter = Ran[0][1]
numP = 0
numT = 1
while True:
    if numP == len(Ran):
        break
    if numT == len(Ran):
        break
    nextBefore = Ran[numT][0]
    if nextBefore < posAfter:
        count += 1
        numT += 1
    else:
        numP = numT
        numT = numP+1
        posAfter = Ran[numP][1]
print(N-count)