#include<bits/stdc++.h>
#define ll long long
#define pii make_pair
#define pb push_back
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define per(i,b,a) for(int i=b;i>=a;--i)
const ll inf = 1145141919810;
using namespace std;
inline ll read(){
    ll x=0,f=1;
    char c=getchar();
    while (c<'0' || c>'9'){
        if (c=='-')  f=-1;
        c=getchar();
    }
    while (c>='0' && c<='9'){
        x=x*10+c-'0';
         c=getchar();
    }
    return x*f;
}
inline void print(ll x){
	if(x < 0) putchar('-'), x = -x;
	if(x > 9) print(x / 10);
	putchar(x % 10 + '0');
	return ;
}
inline void pprint(ll x){print(x); puts("");}
const int N = 2e6 + 7;
ll a[N], sum[N];

int main(){
	int T = read();
	while(T--){
		int n = read();
		int f1 = 1, f2 = 1;
		rep(i, 1, n) {
			a[i] = read();
			if(a[i] >= 0) f1 = 0;
			if(a[i] <= 0) f2 = 0;
		}
		if(n == 1){
			pprint(a[1]);
			continue;
		}
		ll ans = 0, minn = inf;
		rep(i, 1, n){
			ans += abs(a[i]);
			minn = min(minn, abs(a[i]));
		}
		if(f1 || f2){
			pprint(ans - minn * 2);
		}else{
			pprint(ans);
		}
	}
	return 0;
}