#include <iostream>
#include <stdio.h>
#include <algorithm>
using namespace std;
const int N = 100000;
int arr1[N+5];
int main()
{
    int t;
    cin>>t;
    int n;
    while(t--)
    {
        cin>>n;
        for(int i = 0;i<n;i++)
        {
            cin>>arr1[i];
        }
        int a = unique(arr1,arr1+n)-arr1;
        cout<<a<<" "<<endl;
        for(int i = 0;i<a;i++)
        {
            cout<<arr1[i]<<" ";
        }
        cout<<endl;
    }
    
    
    
    return 0;
}

本来想用unique来水掉该题目，但是发现只是交换了顺序，求助！