B = int(input())
N = int(input())
C = [int(input()) for i in range(N)]
canmax = (sum(C) + B) // N
C.sort()
if N % 2:
    M = min(canmax, C[N // 2])
    ans = 0
    for i in range(N):
        ans += abs(C[i] - M)
    print(ans)
else:
    M1 = min(canmax, C[N // 2])
    M2 = min(canmax, C[N // 2 - 1])
    ans1 = 0
    ans2 = 0
    for i in range(N):
        ans1 += abs(C[i] - M1)
        ans2 += abs(C[i] - M2)
    print(min(ans1, ans2))