B=int(raw_input())
N=int(raw_input())
C=[int(raw_input()) for i in range(N)]
C.sort()
candy=0
for c in C:
    candy+=c-C[0]
restCandy=B+candy

possibleHeight=restCandy/N
keyHeight=C[N/2]-C[0]
height=C[0]+min(possibleHeight,keyHeight)
ans=0
for c in C:
    ans+=abs(c-height)
print ans