#include<iostream>
#include<vector>
#include<algorithm>
#include<cstring>
#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 = 5e2 + 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 f[2][N][N];

signed main(){
	T = read();
	while(T--){
		vec.clear();
		
		n = read();
		for(int i=1; i<=n; i++){
			a[i] = read();
			vec.pb(a[i]);
		}
		
		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;
//			printf("a[%d] = %d\n", i, a[i]);
		}
		
		memset(f, -INF, sizeof f);
		f[0][0][0] = 0;
		for(int ii=1; ii<=n; ii++){
			int i=ii&1, lst = (ii-1)&1;
			for(int j=0; j<=m; j++){
				for(int k=0; k<=m; k++){
					f[i][j][k] = max(f[i][j][k], f[lst][j][k]);
					if(a[ii]!=j && a[ii]!=k) f[i][a[ii]][j] = max(f[i][a[ii]][j], f[lst][j][k] + 1);
				}
			}
			
			memset(f[lst], -INF, sizeof f[lst]);
//			for(int j=0; j<=m; j++){
//				for(int k=0; k<=m; k++){
//					printf("f[%d][%d][%d] = %d\n", ii, j, k, f[i][j][k]);
//				}
//				printf("\n");
//			}
		}
		
		int ans = -INF;
		for(int j=0; j<=m; j++){
			for(int k=0; k<=m; k++){
				ans = max(ans, f[n&1][j][k]);
			}
		}
		printf("%lld\n", ans);
	}
}