def binary_search(ok, ng):
  while abs(ok - ng) > 1:
    md = (ng + ok) // 2
    S = sum(min(max(l, md), r) for l, r in zip(L, R))
    if S <= M: ok = md
    else: ng = md
  return ok

for _ in range(T := int(input())):
  N, M = map(int, input().split())
  L = list(map(int, input().split()))
  R = list(map(int, input().split()))
  
  if not sum(L) <= M <= sum(R):
    print(-1); continue

  k = binary_search(min(L), max(R)+1)
  K = [min(max(l, k), r) for l, r in zip(L, R)]
  S = sum(K)
  for i in range(N):
    if S == M: break
    if K[i] == k < R[i]:
      K[i] += 1; S += 1
  
  print(M*(M-1)//2 - sum(k*(k-1)//2 for k in K))