t=int(input())
for tcase in range(t):
    a=list(map(int,input().split()))
    b=list(map(int,input().split()))
    b.sort()
    s=0
    for i in range(0,a[1]):
        s+=b[i]
    print(s-a[0] if s-a[0]>=0 else 0)