import math
x = int(input())
y = int(input())
l = int(input())
cnt = 0
if abs(x) > 0 :
    cnt += 1
if y < 0 :
    cnt += 1
    if x == 0 :
        cnt += 1

cnt += math.ceil(abs(x) / l)
cnt += math.ceil(abs(y) / l)

print(cnt)