#include <stdio.h>
#include <stdlib.h>

int cmp_int_rev (const void *ap, const void *bp) {
  int a = *(int *)ap;
  int b = *(int *)bp;
  
  if (a < b) {
    return 1;
  }
  
  if (a > b) {
    return -1;
  }
  
  return 0;
}

void upheap (int q[][2], int idx) {
  int pidx = (idx-1)/2;
  
  if (idx > 0 && q[pidx][0] > q[idx][0]) {
    int s = q[idx][0];
    q[idx][0] = q[pidx][0];
    q[pidx][0] = s;
    s = q[idx][1];
    q[idx][1] = q[pidx][1];
    q[pidx][1] = s;
    upheap(q, pidx);
  }
  
  return;
}

void downheap (int q[][2], int idx, int size) {
  int ch[2] = { 1000000001, 1000000001 };
  int chidx = -1;
  
  if (2*idx+1 < size) {
    ch[0] = q[2*idx+1][0];
  }
  if (2*idx+2 < size) {
    ch[1] = q[2*idx+2][0];
  }
  
  if (ch[1] < ch[0] && ch[1] < q[idx][0]) {
    chidx = 2*idx+2;
  } else if (ch[0] < q[idx][0]) {
    chidx = 2*idx+1;
  }
  
  if (chidx > 0) {
    int s = q[idx][0];
    q[idx][0] = q[chidx][0];
    q[chidx][0] = s;
    s = q[idx][1];
    q[idx][1] = q[chidx][1];
    q[chidx][1] = s;
    downheap(q, chidx, size);
  }
  
  return;
}

void dequeue (int q[][2], int *size, int *res) {
  res[0] = q[0][0];
  res[1] = q[0][1];
  if (*size > 0) {
    *size -= 1;
    q[0][0] = q[*size][0];
    q[0][1] = q[*size][1];
    downheap(q, 0, *size);
  }
  return;
}

int main () {
  int t = 0;
  int n = 0;
  int m = 0;
  int lr[200000][2] = {};
  
  int res = 0;
  
  long long a[200000] = {};
  
  int q[200000][2] = {};
  
  res = scanf("%d", &t);
  while (t > 0) {
    long long lsum = 0LL;
    long long rsum = 0LL;
    res = scanf("%d", &n);
    res = scanf("%d", &m);
    for (int i = 0; i < n; i++) {
      res = scanf("%d", lr[i]);
      lsum += (long long)lr[i][0];
    }
    for (int i = 0; i < n; i++) {
      res = scanf("%d", lr[i]+1);
      rsum += (long long)lr[i][1];
    }
    if (lsum > (long long)m || rsum < (long long)m) {
      printf("-1\n");
    } else {
      int qsize = 0;
      int idx = 0;
      long long ans = 0LL;
      int tmpsum = 0;
      qsort(lr, n, sizeof(int)*2, cmp_int_rev);
      while (idx < n && m > tmpsum && 1+(m-tmpsum-1)/(n-idx) <= lr[idx][0]) {
        a[idx] = (long long)lr[idx][0];
        tmpsum += lr[idx][0];
        idx++;
      }
      for (int i = idx; i < n; i++) {
        q[qsize][0] = lr[i][1];
        q[qsize][1] = i;
        upheap(q, qsize);
        qsize++;
      }
      while (qsize > 0) {
        int tmp[2] = {};
        if (idx > 0 && 1+(m-tmpsum-1)/qsize >= (int)a[idx-1]) {
          idx--;
          tmpsum -= (int)a[idx];
          a[idx] = 0LL;
          q[qsize][0] = lr[idx][1];
          q[qsize][1] = idx;
          upheap(q, qsize);
          qsize++;
        }
        dequeue(q, &qsize, tmp);
        if (tmp[0] < (m-tmpsum)/(qsize+1)) {
          a[tmp[1]] = (long long)tmp[0];
          tmpsum += tmp[0];
        } else {
          a[tmp[1]] = (long long)((m-tmpsum)/(qsize+1));
          tmpsum += (m-tmpsum)/(qsize+1);
        }
      }
      for (int i = 0; i < n; i++) {
        ans += a[i]*(((long long)m)-a[i]);
      }
      ans /= 2LL;
      printf("%lld\n", ans);
    }
    t--;
  }
  
  return 0;
}