#include <bits/stdc++.h>
using namespace std;
#define all(a) a.begin(), a.end()
void print() { cout << '\n'; }
template <typename T, typename...Args>
void print(T t, Args...args) { cout << t << ' '; print(args...); }
using ll = long long;
const int N = 200010;

void solve () {
    int n;
    cin >> n;
    
    vector<int> a(n);
    for (int i = 0; i < n; i ++) {
        cin >> a[i];
    }
    
    if (n == 1) {
        cout << a[0] << '\n';
        return;
    }
    
    ll ans = -1e18, sum = 0;
    for (int i = 0; i < n; i ++) {
        sum += abs(a[i]);
    }
    for (int i = 0; i < n; i ++) {
        int j = (i + 1) % n;
        ll res = sum - abs(a[i]) - abs(a[j]);
        res += a[i] - a[j];
        ans = max(ans, res);
    }
    cout << ans << '\n';
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	int t = 1; 
	cin >> t;
	while(t --) {
	    solve();
	}

	return 0;
}