X = abs(int(input()))
Y = abs(int(input()))
L = int(input())
count_x = count_y = x = y = 0
while X > x:
    count_x += 1
    x += L
while Y > y:
    count_y += 1
    y += L
if X==0 or Y==0:
    print(count_x+count_y)
else:
    print(count_x+count_y+1)