B = int(input())
N = int(input())
C = [int(input()) for _ in range(N)]
INF = 10 ** 10 + 1
maxx = (B + sum(C)) // N


def calc(x):
    tmp = 0
    for i in range(N):
        tmp += abs(C[i] - x)
    return tmp

lb = 0
ub = maxx + 1
while ub - lb > 1:
    mid1 = 2 * lb / 3 + ub / 3
    mid2 = lb / 3 + 2 * ub / 3
    if calc(mid1) < calc(mid2):
        ub = mid2
    else:
        lb = mid1

lb = int(lb)
ans = INF
for j in range(lb, min(int(lb) + 1, maxx) + 1):
    tmp = 0
    for i in range(N):
        tmp += abs(C[i] - j)
    ans = min(ans, tmp)
print(ans)