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

C.sort()

T=10**20
for i in range(min(B+1,N)):
    if i!=0:
        C[i-1]+=1

    U=0
    S=sum(C)
    for j in range(N):
        U+=abs(C[j]-S//N)

    T=min(T,U+i)

print(T)