ncase=int(raw_input())
for i in range(ncase):
    li=map(int,raw_input().strip().split())
    m_li=map(int,raw_input().strip().split())
    m_li.sort()
    sum=0
    for j in range(li[1]):
        sum=sum+m_li[j]
    sum=sum-li[0]
    if sum>0:
        print sum
    else:
        print 0