x, y, l = int(input()), int(input()), int(input())
turn = 0
if(y < 0):
    turn += 2
else:
    turn += 1
if(abs(y) % l == 0):
    turn += abs(y) // l
else:
    turn += abs(y) // l + 1
if(abs(x) % l == 0):
    turn += abs(x) // l
else:
    turn += (abs(x) // l + 1)
if(x == 0 and y >= 0):
    turn -= 1
print(turn)