B=int(input())
N=int(input())
C=[int(input()) for i in range(N)]

x=sum(C)//N
ANS=1<<100

for xx in C:

    if  xx*N>sum(C)+B:
        i=(sum(C)+B)//N
    else:
        i=xx

    score=0

    for c in C:
        score+=abs(i-c)

    ANS=min(ANS,score)

print(ANS)