#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    int a[n];
    for (int i = 0; i < n; i++) cin >> a[i];
    for (int i = 0; i < n; i += 2) {
      cout << a[i + 1] << " " << -a[i] << " ";
    }
    cout << endl;
  }
  return 0;
}
