#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int t;
    cin >> t;
    while (t--) {
        int n;
        cin >> n;
        vector<int> a(n);
        for (int &x : a) cin >> x;
        sort(a.begin(), a.end());
        cout << a[n - 1] - a[0] << "\n";
    }
    return 0;
}