N = int(input())
s = [tuple(map(int, input().split())) for i in range(N)]

s.sort(key=lambda x: x[1])

t = list(map(lambda j:(j[0]-j[1]+1, j[0]+j[1]-1), s))
NN = len(t)
dobon = []

for k, k_l in enumerate(t):
  if k in dobon:
    break
  for l in range(k+1, NN):
    if l in dobon:
      pass
    else:
      if int(k_l[1]) <= int(t[l][1]):
        if (t[l][0] <= k_l[1]) and (k_l[1] <= t[l][1]):
          N -= 1
          dobon.append(l)
          break
      else:
        if (t[l][0] <= k_l[0]) and (k_l[0] <= t[l][1]):
          N -= 1
          dobon.append(l)
          break

print(N)