B = int(input())
N = int(input())
C = [int(input()) for _ in range(N)]
INF = 10 ** 10 + 1
maxx = (B + sum(C)) // N
C.sort()
D = [min(maxx, C[N // 2])]
if N % 2 == 0:
    D.append(min(maxx, C[N // 2 - 1]))
ans = INF
for j in D:
    tmp = 0
    for i in range(N):
        tmp += abs(C[i] - j)
    ans = min(ans, tmp)

print(ans)