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

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