X = int(input())
Y = int(input())
L = int(input())


north_cnt = int(Y / L)
east_cnt = 0

if Y % L != 0:
    north_cnt += 1

if Y < 0:
    north_cnt += 1

if X != 0:
    east_cnt += (1 + int(abs(X) / L))
    if X % L != 0: east_cnt += 1

print(north_cnt + east_cnt)