def read_data():
    B = int(input())
    N = int(input())
    Cs = [int(input()) for i in range(N)]
    return B, N, Cs

def solve(B, N, Cs):
    Cs.sort()
    median = Cs[N//2]
    min_move = sum([abs(median - c) for c in Cs])
    surplus = sum([c - median for c in Cs])
    if surplus + B >= 0:
        return min_move
    return binary_search(Cs, median, B)

def binary_search(Cs, median, B):
    lower = 0
    upper = median
    while upper > lower + 1:
        middle = (lower + upper) // 2
        surplus = sum([c - middle for c in Cs])
        if surplus + B >= 0:
            lower = middle
        else:
            upper = middle
    min_move = sum([abs(lower - c) for c in Cs])
    return min_move

if __name__ == '__main__':
    B, N, Cs = read_data()
    print(solve(B, N, Cs))