N, K = map(int, input().split(' '))
A = list(map(int, (input().split(' '))))

L = 0

O = sorted(A,reverse = True)

for i in range(K):
    if 0 <= O[i]:
        L += O[i]
    elif L == 0:
        L += O[0]
    else:
        break
    

print(L)