X, Y, L = [int(input()) for _ in range(3)]

C = 0
if X == 0 and Y > 0:
    C += 0
elif X != 0 and Y > 0:
    C += 1
else:
    C += 2

C += -(-abs(X)//L)
C += -(-abs(Y)//L)

print(C)