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

count = 0

if Y < 0:
    count += 2
elif X != 0:
    count += 1

if Y < 0:
    Y = -(Y * 1)

if X < 0:
    X = -(X * 1)

co_x = -(-X // L)
co_y = -(-Y // L)
    
count2 = count + co_x + co_y

print(count2)