X = int(input())
Y = int(input())
L = int(input())
C = 0
def robot(XY, L):
    XY = divmod(abs(XY), L)
    if XY[1] == 0:
       return XY[0]
    else:
       return XY[0] + 1

if Y < 0:
    C += 2
else:
    if X != 0:
        C += 1

print(robot(X, L,) + robot(Y, L,) + C)