def main():
    N, K = map(int,input().split())
    A = list(map(int,input().split()))
    A_sort = reversed(sorted(A))
    ans = 0
    for i,Ai in enumerate(A_sort):
        if i+1 > K:break
        if Ai <= 0 and i + 1 > 1 :break
        ans += Ai
    print(ans)


if __name__ == '__main__':
    main()