#include<bits/stdc++.h>
using namespace std;
//ofstream file("output0.txt");
void solve()
{
    int n,t1,t2; cin>>t1>>t2;
    cin>>n;
    int a[n+1],b[n+1];
    int sum=0;
    for(int i=1;i<=n;i++) cin>>a[i];
    for(int i=1;i<=n;i++) cin>>b[i];
    sum = a[n];
    int ans=1e9;
    for(int i=1;i<=n;i++)
    {
        if(b[i]>min(t1,t2))
        {
            ans = min(ans,abs(sum-a[i]*2));
        }
    }
    
    if (ans == 1e9) ans = -1;
    cout<<ans<<endl;
    //file<<ans<<endl;
}
int main(){
    //freopen("input0.txt","r",stdin);
    int t; cin>>t; while(t--) solve();}