#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <cstdlib>
using namespace std; 

const long long MAXN = 1e6 + 10;

inline long long read() {
	long long x = 0, f = 1;
	char ch = getchar();
	while (!isdigit(ch)) {
		if (ch == '-') f = -1;
		ch = getchar();
	}
	while (isdigit(ch)) {
		x = x * 10 + ch - '0';
		ch = getchar();
	}
	return x * f;
}

long long n, a[MAXN];

int main() {
	long long t = read();
	for (long long u = 1; u <= t; u++) {
		n = read();
		bool flag = false;
		for (long long i = 1; i <= n; i++) {
			a[i] = read();
			if (i != 1 && a[i] * a[i - 1] < 0) flag = true;
		}
		if (a[1] * a[n] < 0) flag = true;
		if (n == 1) printf("%lld\n", a[1]);
		else {
			if (flag) {
				long long ans = 0;
				for (long long i = 1; i <= n; i++) {
					ans += abs(a[i]);
				}
				printf("%lld\n", ans);
			} else {
				sort(a + 1, a + 1 + n);
				long long ans = 0;
				for (long long i = 2; i <= n; i++) ans += a[i];
				ans -= a[1];
				printf("%lld\n", ans);
			} 
		}
	}
	return 0;
}