def bis(ok, ng):
  def is_ok(md):
    ttl = sum(min(max(L[i], md), R[i]) for i in range(n))
    return ttl <= m
  
  while abs(ok - ng) > 1:
    md = (ng + ok) // 2
    if is_ok(md): ok = md
    else: ng = md
  return ok

T = int(input())
for _ in range(T):
  n, m = map(int, input().split())
  L = list(map(int, input().split()))
  R = list(map(int, input().split()))

  if m < sum(L) or sum(R) < m:
    print(-1)
    continue
  
  k = max(R) if sum(R) == m else bis(min(L), max(R))
  cnt = sorted([min(max(L[i], k), R[i]), i] for i in range(n))
  ttl = sum(cnt[i][0] for i in range(n))
  i = 0
  while ttl < m:
    if cnt[i][0] < R[cnt[i][1]]:
      cnt[i][0] += 1
      ttl += 1
    i += 1
  ans = sum(cnt[i][0] * (m - cnt[i][0]) for i in range(n)) // 2
  print(ans)