B = int(input())
N = int(input())
C = [int(input()) for i in range(N)]
canmax = (sum(C) + B) // N
M1 = min(canmax, sum(C) // N)
M2 = min(canmax, M1 + 1)

ans = 0
for i in range(N):
    ans += abs(C[i] - M1)

ans2 = 0
for i in range(N):
    ans2 += abs(C[i] - M2)

print(min(ans, ans2))