n = int(input())

xl = (map(int, input().split()) for _ in range(n))
w = [(x - l, x + l) for x, l in xl]
w = sorted(w, key=lambda x: x[1])
cur = w[0][1]
res = 1
for l, r in w[1:]:
    if l >= cur:
        res += 1
        cur = r
print(res)
