n,k = map(int,input().split())
a = list(map(int,input().split()))
a_so = sorted(a,reverse=True)
ans = 0

for i in range(k):
    if i == 0:
        ans += a_so[i]
    elif a_so[i] < 0:
        continue
    else:
        ans += a_so[i]
print(ans)