x = abs(int(input()))
y = abs(int(input()))
k = int(input())
count = 0
x_move, y_move = 0, 0
while x > 0:
    count = count + 1
    x_move = 1
    x = x - k
while y > 0:
    count = count + 1
    y_move = 1
    y = y -k
# move direction
if x_move * y_move == 1:
    count = count + 1
print(count)