x = int(input())
y = int(input())
step = int(input())

if x == 0:
    count = 0
elif y > 0:
    count = 1
else:
    count = 2


if abs(x)%step == 0:
    count += abs(x)/step
else:
    count += int(abs(x)/step) + 1
    
if abs(y)%step == 0:
    count += abs(y)/step
else:
    count += int(abs(y)/step) + 1
    
print(int(count))