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

x_move = -(-abs(X)//L)
y_move = -(-abs(Y)//L)
move = x_move+y_move

if Y >= 0:
    if X==0:
        print(move)
    else:
        print(move+1)
    exit()

else:
    print(move+2)