X = int(input())
Y = int(input())
L = int(input())

step = 0

if((X >= 0) and (Y > 0)):
    step += 1
elif((X >= 0) and (Y < 0)):
    step += 2
    Y *= -1
elif((X < 0) and (Y > 0)):
    step += 1
    X *= -1
elif((X < 0) and (Y < 0)):
    step += 2
    X *= -1
    Y *= -1

step += int(X/L)
if((X % L) != 0):
    step += 1

step += int(Y/L)
if((Y % L) != 0):
    step += 1

print(step)