D2

#include <bits/stdc++.h>

using namespace std;

#define ll     long long
#define _test   int _TEST; cin>>_TEST; while(_TEST--)

int main()
{
    _test
    {
        ll int n, m;
        cin>>n>>m;

        vector<int> a(n), b(n);

        a[0] = 1;
        for(int i=1; i<n; i++)
            cin>>a[i];

        for(auto &e: b)     cin>>e;

        multiset<int> msta, mstb;
        for(auto e: a)      msta.insert(e);
        for(auto e: b)      mstb.insert(e);

        ll int cnt = 0;
        int sz = n;

        ll int ans = 0;

        while(msta.size())
        {
            if(sz == 1)
            {
                if(*mstb.rbegin() > *msta.begin())
                {
                    ll int x = *mstb.rbegin();
                    cnt++;

                    cnt = n - cnt;

                    if(m >= x)
                        ans = cnt*1ll*(x-1) + (cnt+1)*1ll*(m-x+1);
                    else
                        ans = cnt*1ll*m;
                }
                else
                {
                    cnt = n - cnt;
                    ans = cnt*1ll*m;
                }

                break;
            }

            if(mstb.upper_bound(*msta.rbegin()) != mstb.end())
            {
                cnt++;
                mstb.erase(mstb.upper_bound(*msta.rbegin()));
            }

            msta.erase(--msta.end());
            sz--;
        }

        cout<<ans<<"\n";
    }
}