#include <bits/stdc++.h>   using namespace std;   int main() {     int n, m;     cin >> n;     for (int k = 0; k < n; k++) {       cin >> m;       for (int i = 0; i < m / 2; i++) {         int fir, sec;         cin >> fir >> sec;         if (fir > 0 && sec > 0) {           cout << sec <<     << -fir <<    ;         } else if (fir < 0 && sec < 0) {           cout << -sec <<     << fir <<    ;         } else if (fir > 0 && sec < 0) {           cout << -sec <<     << fir <<    ;         } else if (fir < 0 && sec > 0) {           cout << sec <<     << -fir <<    ;         }       }       cout << endl;     }   }   