Комплекти

using System.Runtime.CompilerServices;

class Solution
{
    [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
    private static ulong Fact(ulong n)
    {
        ulong ret = 1;
        for (ulong i = 1; i <= n; i++)
        {
            ret *= i;
        }
        return ret;
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
    private static ulong C(ulong n, ulong r) => Fact(n) / (Fact(r) * Fact(n - r));

    public static void Main()
    {
        int tests = Int32.Parse(Console.ReadLine()!);
        for (int testNo = 0; testNo < tests; testNo++)
        {
            ulong[] input = Console.ReadLine()!.Split(' ', 4).Select(UInt64.Parse).ToArray();
            Console.WriteLine(C(input[2], input[0]) * C(input[3], input[1]));
        }
    }
}