#include <bits/stdc++.h>   int main() {     int q;     std::cin >> q;     while (q--) {       int n;       std::cin >> n;       std::vector<int> a(n);       for (int i = 0; i < n; ++i) {         std::cin >> a[i];       }       for (int i = 0; i < n; i += 2) {         std::cout << -a[i + 1] <<     << a[i] <<    ;       }       std::cout <<   n ;     }   }   