#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
#define int ll
#define lc (rt<<1)
#define rc (rt<<1|1)
#define mid (l+r>>1)
#define rg register
#define pb push_back
#define ppb pop_back
#define mkp make_pair
#define prq_mn(x) priority_queue<x, vector<x>, greater<x> >
#define prq_mx(x) priority_queue<x, vector<x>, less<x> >
#define fi first
#define se second
#define DEBUG printf("Debug on line %d\n", __LINE__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
const int N = 2e5 + 5;
const int MXLEN = 5;
const int INF = 0x3f3f3f3f;

template <typename T> bool updmax(T& a, T b) {return a<b ? a=b, 1 : 0;}
template <typename T> bool updmin(T& a, T b) {return a>b ? a=b, 1 : 0;}

inline int read(){
	int n=0, f=1; char ch = getchar();
	for(; !isdigit(ch); ch=getchar()) if(ch == '-') f=-1;
	for(; isdigit(ch); ch=getchar()) n=n*10+ch-'0';
	return n*f;
}

int T;
int n, m;
int a[N];
vector<int> vec;
int mx[N], mxk[N], smx[N], smxk[N];
vector<int> lst; bool vis[N];

void addlst(int x){
	if(!vis[x]) vis[x] = 1, lst.pb(x);
	else {for(auto it=lst.begin(); it!=lst.end(); it++) if(*it == x) {lst.erase(it); break;} lst.pb(x);}
	if(lst.size() > MXLEN) lst.erase(lst.begin());
}

signed main(){
	T = read();
	while(T--){
		vec.clear();
		lst.clear();
		
		n = read();
		for(int i=1; i<=n; i++) a[i] = read(), vec.pb(a[i]);
		for(int i=0; i<=n; i++) mx[i] = mxk[i] = smx[i] = smxk[i] = -INF, vis[i] = 0;
		
		sort(vec.begin(), vec.end());
		vec.erase(unique(vec.begin(), vec.end()), vec.end());
		m = vec.size();
		for(int i=1; i<=n; i++) a[i] = lower_bound(vec.begin(), vec.end(), a[i]) - vec.begin() + 1;
		
		int ans = -INF;
		mx[0] = mxk[0] = 0;
		addlst(0);
		for(int i=1; i<=n; i++){
            mx[a[i]] = mxk[a[i]] = smx[a[i]] = smxk[a[i]] = 0;
			for(int j: lst){
				if(j == a[i]) continue;
				int x = mx[j]+1, k = mxk[j];
				if(k == a[i]) x = smx[j]+1, k = smxk[j];
				if(x > mx[a[i]]) smx[a[i]] = mx[a[i]], smxk[a[i]] = mxk[a[i]], mx[a[i]] = x, mxk[a[i]] = j;
				else if(x > smx[a[i]]) smx[a[i]] = x, smxk[a[i]] = j;
				ans = max(ans, x);
			}
			addlst(a[i]);
			
//			for(int j=0; j<=m; j++){
//				printf("mx[%d][%d] = %d\n", i, j, mx[j]);
//				printf("mxk[%d][%d] = %d\n", i, j, mxk[j]);
//				printf("smx[%d][%d] = %d\n", i, j, smx[j]);
//				printf("smxk[%d][%d] = %d\n", i, j, smxk[j]);
//			}
		}
		
		printf("%lld\n", ans);
	}
}