from math import ceil
def MIN(X, Y, L):
  if Y >= 0 and X == 0:
    return ceil(Y / L)
  elif Y >= 0 and X > 0:
    return ceil(Y / L) + 1 + ceil(abs(X) / L)
  elif Y < 0:
    return 1 + ceil(abs(X) / L) + 1 + ceil(abs(Y) / L)
X = int(input())
Y = int(input())
L = int(input())
print(MIN(X, Y, L))