b = int(input())
n = int(input())
c = sorted([int(input()) for _ in range(n)])

l1 = []
x = c[n//2]
for i in c:
    l1.append(abs(x-i))

l2 = []
x = (sum(c) + b) // n
for i in c:
    l2.append(abs(x-i))


# print(sum(l1), sum(l2))
print(max(sum(l1), sum(l2)))