80分wa后五个点求调，闭关，大佬帮帮忙吧！！！

#include <bits/stdc++.h>
using namespace std;
int main() 
{
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
    int t;
    cin >> t;
    while (t--) 
	{
        int n;
        cin >> n;
        vector<long long> a(n);
        unordered_set<long long> s;
        long long x = 0;
        for (int i = 0; i < n; ++i) 
		{
            cin >> a[i];
            s.insert(a[i]);
            x ^= a[i];
        }
        long long m = 0;
        while (s.count(m)) m++;
        if (x == m) 
		{
            cout << 0 << endl;
            cout << endl;
            continue;
        }
        long long y = x ^ m;
        if (y != m) cout << 1 << endl << y << endl;
	    else 
		{
            long long t = m ^ (m + 1);
            cout << 2 << endl << m << " " << t << endl;
        }
    }
    return 0;
}