def func(n, candy_list, b):
    ans = 0
    for c in candy_list:
        if c > n:
            d = c - n
            ans += d
            b += d
        elif c < n:
            d = n - c
            if d > b:
                return 10 ** 15
            ans += d
            b -= d

    return ans


def main():
    b = int(input())
    n = int(input())
    candy_list = sorted([int(input()) for _ in range(n)], reverse=True)

    ans = 10 ** 15
    for x in set(candy_list):
        ans = min(ans, func(x, candy_list, b))
    print(ans)
    
    
if __name__ == '__main__':
    main()