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

count = 0

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

co_x = -(-X // L)
co_y = -(-Y // L)

if co_x < 0:
    co_x = -(co_x * 1)
elif co_y < 0:
    co_y = -(co_y * 1)
    
count2 = count + co_x + co_y

print(count2)