# No.48 ロボットの操縦
X, Y, L = [int(input()) for i in range(3)]

if X == 0 and Y >= 0:
    result = 0
elif Y > 0:
    result = 1
else:
    result = 2

X = abs(X)
Y = abs(Y)

if X % L == 0:
    result += X // L
else:
    result += X // L + 1

if Y % L == 0:
    result += Y // L
else:
    result += Y // L + 1

print(result)