description: Vupsen and Pupsen were gifted an integer array. Since Vupsen doesn't like the number 0, he threw away all numbers equal to 0 from the array. As a result, he got an array a of length n.
  
  Pupsen, on the contrary, likes the number 0 and he got upset when he saw the array without zeroes. To cheer Pupsen up, Vupsen decided to come up with another array b of length n such that ∑_{i=1}^{n}a_i ⋅ b_i=0. Since Vupsen doesn't like number 0, the array b must not contain numbers equal to 0. Also, the numbers in that array must not be huge, so the sum of their absolute values cannot exceed 10^9. Please help Vupsen to find any such array b!
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 100) — the number of test cases. The next 2 ⋅ t lines contain the description of test cases. The description of each test case consists of two lines.
  
  The first line of each test case contains a single integer n (2 ≤ n ≤ 10^5) — the length of the array.
  
  The second line contains n integers a_1, a_2, …, a_n (-10^4 ≤ a_i ≤ 10^4, a_i ≠ 0) — the elements of the array a.
  
  It is guaranteed that the sum of n over all test cases does not exceed 2 ⋅ 10^5.
  
  Output
  
  For each test case print n integers b_1, b_2, …, b_n — elements of the array b (|b_1|+|b_2|+… +|b_n| ≤ 10^9, b_i ≠ 0, ∑_{i=1}^{n}a_i ⋅ b_i=0).
  
  It can be shown that the answer always exists.
  
  Example
  
  Input
  
  
  3
  2
  5 5
  5
  5 -2 10 -9 4
  7
  1 2 3 4 5 6 7
  
  
  Output
  
  
  1 -1
  -1 5 1 -1 -1
  -10 2 2 -3 5 -1 -1
  
  Note
  
  In the first test case, 5 ⋅ 1 + 5 ⋅ (-1)=5-5=0. You could also print 3 -3, for example, since 5 ⋅ 3 + 5 ⋅ (-3)=15-15=0
  
  In the second test case, 5 ⋅ (-1) + (-2) ⋅ 5 + 10 ⋅ 1 + (-9) ⋅ (-1) + 4 ⋅ (-1)=-5-10+10+9-4=0.
solution: import java.util.*;
  
  import java.io.*;
  
  public class ferrisWheel {
  	static PrintWriter pw = new PrintWriter(System.out);
  	static Scanner sc = new Scanner(System.in);
  
  	public static long gcd(long a, long b) {
  		if (b == 0)
  			return a;
  		else
  			return gcd(b, a % b);
  	}
  
  	public static void main(String[] args) throws IOException, InterruptedException {
  		int t = sc.nextInt();
  		while (t-- > 0) {
  			int n = sc.nextInt();
  			int[] arr = sc.nextIntArray(n);
  			long[] ans = new long[n];
  			for (int i = 0; i < n; i += 2) {
  				if (i == n - 1)
  					break;
  				long x = gcd(Math.abs(arr[i]), Math.abs(arr[i + 1]));
  				ans[i] = arr[i + 1] / x;
  				ans[i + 1] = -arr[i] / x;
  			}
  			if (n % 2 == 1) {
  				long x = gcd(Math.abs(arr[n - 1]), arr[n - 2]);
  				if (ans[n - 2] < 0) {
  					ans[n - 2] += arr[n - 1] / x;
  					ans[n - 1] = -arr[n - 2] / x;
  					if (ans[n - 2] == 0) {
  						ans[n - 2] = arr[n - 1] / x;
  						ans[n - 1] *= 2;
  					}
  				} else {
  					ans[n - 2] -= arr[n - 1] / x;
  					ans[n - 1] = arr[n - 2] / x;
  					if (ans[n - 2] == 0) {
  						ans[n - 2] = -arr[n - 1] / x;
  						ans[n - 1] *= 2;
  					}
  				}
  			}
  			for (long x : ans)
  				pw.print(x + " ");
  			pw.println();
  		}
  		pw.flush();
  	}
  
  	static class pair implements Comparable<pair> {
  		long x;
  		long y;
  
  		public pair(long x, long y) {
  			this.x = x;
  			this.y = y;
  		}
  
  		public String toString() {
  			return x + " " + y;
  		}
  
  		public boolean equals(Object o) {
  			if (o instanceof pair) {
  				pair p = (pair) o;
  				return p.x == x && p.y == y;
  			}
  			return false;
  		}
  
  		public int hashCode() {
  			return new Long(x).hashCode() * 31 + new Long(y).hashCode();
  		}
  
  		public int compareTo(pair other) {
  			if (this.x == other.x) {
  				return Long.compare(this.y, other.y);
  			}
  			return Long.compare(this.x, other.x);
  		}
  	}
  
  	static class tuble implements Comparable<tuble> {
  		int x;
  		int y;
  		int z;
  
  		public tuble(int x, int y, int z) {
  			this.x = x;
  			this.y = y;
  			this.z = z;
  		}
  
  		public String toString() {
  			return x + " " + y + " " + z;
  		}
  
  		public int compareTo(tuble other) {
  			if (this.x == other.x) {
  				if (this.y == other.y) {
  					return this.z - other.z;
  				}
  				return this.y - other.y;
  			} else {
  				return this.x - other.x;
  			}
  		}
  	}
  
  	static class PairPoint {
  		pair p1;
  		pair p2;
  
  		public PairPoint(pair p1, pair p2) {
  			this.p1 = p1;
  			this.p2 = p2;
  
  		}
  
  		public String toString() {
  			return p1.toString() + p2.toString();
  		}
  
  		public boolean equals(PairPoint pp) {
  			if (p1.equals(pp.p1) && p2.equals(pp.p2))
  				return true;
  			return false;
  		}
  
  	}
  
  	static class Scanner {
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream s) {
  			br = new BufferedReader(new InputStreamReader(s));
  		}
  
  		public Scanner(String file) throws IOException {
  			br = new BufferedReader(new FileReader(file));
  		}
  
  		public Scanner(FileReader r) {
  			br = new BufferedReader(r);
  		}
  
  		public String next() throws IOException {
  			while (st == null || !st.hasMoreTokens())
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  
  		public String readAllLines(BufferedReader reader) throws IOException {
  			StringBuilder content = new StringBuilder();
  			String line;
  
  			while ((line = reader.readLine()) != null) {
  				content.append(line);
  				content.append(System.lineSeparator());
  			}
  
  			return content.toString();
  		}
  
  		public int nextInt() throws IOException {
  			return Integer.parseInt(next());
  		}
  
  		public long nextLong() throws IOException {
  			return Long.parseLong(next());
  		}
  
  		public String nextLine() throws IOException {
  			return br.readLine();
  		}
  
  		public double nextDouble() throws IOException {
  			String x = next();
  			StringBuilder sb = new StringBuilder("0");
  			double res = 0, f = 1;
  			boolean dec = false, neg = false;
  			int start = 0;
  			if (x.charAt(0) == '-') {
  				neg = true;
  				start++;
  			}
  			for (int i = start; i < x.length(); i++)
  				if (x.charAt(i) == '.') {
  					res = Long.parseLong(sb.toString());
  					sb = new StringBuilder("0");
  					dec = true;
  				} else {
  					sb.append(x.charAt(i));
  					if (dec)
  						f *= 10;
  				}
  			res += Long.parseLong(sb.toString()) / f;
  			return res * (neg ? -1 : 1);
  		}
  
  		public long[] nextlongArray(int n) throws IOException {
  			long[] a = new long[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextLong();
  			return a;
  		}
  
  		public Long[] nextLongArray(int n) throws IOException {
  			Long[] a = new Long[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextLong();
  			return a;
  		}
  
  		public int[] nextIntArray(int n) throws IOException {
  			int[] a = new int[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextInt();
  			return a;
  		}
  
  		public Integer[] nextIntegerArray(int n) throws IOException {
  			Integer[] a = new Integer[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextInt();
  			return a;
  		}
  
  		public boolean ready() throws IOException {
  			return br.ready();
  		}
  
  	}
  
  }