func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long LLmn = LLONG_MIN;   const long long LLmx = LLONG_MAX;   const long long MOD = 1e6 + 3;   const long long N = 1e9 + 7;   const long double PI = 3.14159265358979323846;   long long gcd(long long a, long long b) {     if (a == 0) {       return b;     }     return gcd(b % a, a);   }   long long lcm(long long a, long long b) { return a * b / gcd(a, b); }   pair<int, int> w[9] = {make_pair(-1, 0), make_pair(0, -1),  make_pair(1, 0),                          make_pair(0, 1),  make_pair(-1, -1), make_pair(0, 1),                          make_pair(1, -1), make_pair(1, 1)};   void solve() {     long long n;     cin >> n;     long long a[n];     for (long long i = 0; i < n; i++) cin >> a[i];     if (n & 1) {       if (a[0] + a[1] != 0)         cout << -a[2] <<     << -a[2] <<     << a[0] + a[1] <<    ;       else if (a[0] + a[2] != 0)         cout << -a[1] <<     << a[0] + a[2] <<     << -a[1] <<    ;       else         cout << a[1] + a[2] <<     << -a[0] <<     << -a[0] <<    ;       for (long long i = 3; i < n; i += 2) {         if (i + 1 < n) cout << a[i + 1] <<     << -a[i] <<    ;       }       cout <<   n ;       ;     } else {       for (long long i = 0; i < n; i += 2) {         if (i + 1 < n) cout << a[i + 1] <<     << -a[i] <<    ;       }       cout <<   n ;       ;     }   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(NULL);     ;     long long t;     cin >> t;     while (t--) solve();   }   