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

sumC = sum(C)
CC = sorted(set(C))
m = len(CC)
ans = 10**18
for i in range(m):
    c = CC[i]
    if c * n > sumC + b:
        break
    res = 0
    for j in range(n):
        res += abs(C[j] - c)
    ans = min(ans, res)
print(ans)