#include<bits/stdc++.h>
using namespace std;
#define ll long long
int main(){
    ll t;
    cin >> t;
    while (t--)
    {
        ll n;
        cin >> n;
        deque <ll> a(n);
        for(ll i=0;i<n;i++)cin>> a[i];
        sort(a.begin(),a.end());
        ll sum = 0;
            sum+=a[n-1];
            a.pop_back();

            sum-=a.back();
      
        cout << sum << endl;
    }
}