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

def cost(x):
    add = sum(max(0, x - ci) for ci in c)
    if add > b:
        return float('inf')  
    remove = sum(max(0, ci - x) for ci in c)
    return add + remove

l = min(c)
r = max(c) + b

while r - l > 3:
    m1 = (2 * l + r) // 3
    m2 = (l + 2 * r) // 3
    if cost(m1) < cost(m2):
        r = m2
    else:
        l = m1

ans = min(cost(x) for x in range(l, r + 1))
print(ans)