import sys
from itertools import permutations
import heapq
from collections import deque
import random

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

def solve(n,m,L,R):
    if m < sum(L)  or sum(R) < m:
        return -1
    
    cnt = [L[i] for i in range(n)]
    rest = m - sum(cnt)

    def cond(k):
        check = 0
        for i in range(n):
            if L[i] <= k:
                check += min(k,R[i]) - L[i]
        return check <= rest
    
    ok = min(L)
    ng = max(R) + 1
    while ng-ok>1:
        mid = (ok+ng)//2
        if cond(mid):
            ok = mid
        else:
            ng = mid
    
    
    
    for i in range(n):
        cnt[i] = max(ok,L[i])
    
    
    rest = m - sum(cnt)
    idx = [i for i in range(n)]
    idx.sort(key=lambda i:cnt[i])
    for i in range(rest):
        cnt[i] += 1
    
    res = m * (m-1)//2
    for i in range(n):
        res -= cnt[i] * (cnt[i]-1) //2
    
    return res

for _ in range(int(input())):
    n,m = mi()
    L = li()
    R = li()

    print(solve(n,m,L,R))