n = int(input())
inp = (map(int, input().split()) for i in range(n))
p = sorted(list((a + b, a - b) for a, b in inp))
a = list(y for x, y in p)
d = []
for x in a:
    low, high = -1, len(d) # >, <=
    while high - low > 1:
        mid = (low + high) >> 1
        if d[mid] > x:
            low = mid
        else:
            high = mid
    if high == len(d):
        d.append(x)
    else:
        d[high] = x
print(len(d))