def main():
    x = int(input())
    y = int(input())
    l = int(input())

    num_op = 0

    if y == 0:
        if x != 0:
            num_op += 1
            num_op += return_op_cnt(x, l)
    elif y > 0:
        num_op += return_op_cnt(y, l)
        if x != 0:
            num_op += 1
            num_op += return_op_cnt(x, l)
    elif y < 0:
        num_op += 2
        num_op += return_op_cnt(y, l)
        num_op += return_op_cnt(x, l)

    print(num_op)

def return_op_cnt(cor, l):
    dis = abs(cor)

    if dis%l == 0:
        return dis//l
    else:
        return dis//l + 1

if __name__ == '__main__':
    main()