#include <algorithm>
#include <cstdio>
#include <cstring>
#include <map>
#include <queue>
#define FILEIO(filename) (freopen(filename ".in", "r", stdin), freopen(filename ".out", "w", stdout))
typedef long long ll;
typedef unsigned long long ull;
const int N = 200005;
int Test, n, a[N];
std::map<int, int> mp;
std::priority_queue<std::pair<int, int>> que[N];
inline int get(int x, int lim)
{
    if(que[x].top().second != lim)
        return que[x].top().first;
    auto pr = que[x].top();
    que[x].pop();
    while(que[x].top().second == pr.second)
        que[x].pop();
    int res = que[x].top().first;
    que[x].push(pr);
    return res;
}
int main(void)
{
    scanf("%d", &Test);
    while (Test--)
    {
        scanf("%d", &n), mp.clear();
        int nn = 0, cnt = 0;
        for (int i = 1, x; i <= n; ++i)
        {
            scanf("%d", &x);
            if (mp.count(x))
                x = mp[x];
            else
                x = (mp[x] = ++cnt);
            if (nn == 0 || a[nn] != x)
                a[++nn] = x;
        }
        for (int i = 1; i <= cnt; ++i)
        {
            while (!que[i].empty())
                que[i].pop();
            que[i].push({1, 0});
        }
        for (int i = 1; i <= nn;++i)
            for (int j = std::max(1, i - 2);j < i;++j)
                if(a[i] != a[j])
                {
                    int v = get(a[j], a[i]) + 1;
                    que[a[i]].push({v, a[j]});
                }
        int ans = 0;
        for (int i = 1;i <= cnt;++i)
            ans = std::max(ans, que[i].top().first);
        printf("%d\n", ans);
    }
    return 0;
}