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