C_First_or_Second.cpp

#include <bits/stdc++.h>
using namespace std;
// First you make it work, then you can always make it beautiful
#define int long long
const int inf = 1e18;

void solve() {
    int n;
    cin >> n;
    vector<int> v(n+1), pre(n + 1), suff(n + 2);
    for(int i=1;i<=n;i++) {
        cin >> v[i];
    }

    for(int i=2;i<=n;i++) {
        pre[i] = pre[i-1];
        if(v[i] > 0) pre[i] += v[i];
        else pre[i] -= v[i];
    }

    for(int i=n;i>0;i--) {
        suff[i] = suff[i+1] + v[i]; 
    }

    int ans = -suff[2];
    for(int i=2;i<=n;i++) {
        ans = max(ans, v[1] + pre[i-1] - suff[i+1]);
    }
    cout << ans << "\n";

}


int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    int _;
    cin >> _;
    while (_-->0) {
        solve();
    }

    return 0;
}