#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
#define ll long long
#define mod 1000000007
// #define int long long
#define all(x)      x.begin(),x.end()
#define allr(x)     x.rbegin(),x.rend()
#define CheckBit(x,k)   (x & (1LL << k))
#define SetBit(x,k)     (x |= (1LL << k))
#define ClearBit(x,k)   (x &= ~(1LL << k))
#define LSB(mask)       __builtin_ctzll(mask)
#define MSB(mask)       63-__builtin_clzll(mask) 
#define print(x)    cout << #x << " : " << x << endl
#define error1(x)   cerr << #x << " = " << (x) <<endl
#define coutall(v)  for(auto &it: v) cout<<it<<' '; cout<<endl
#define Abid_52     ios::sync_with_stdio(false);cin.tie(0),cin.tie(0)
#define error2(a,b) cerr<<"( "<<#a<<" , "<<#b<<" ) = ( "<<(a)<<" , "<<(b)<<" )\n"
#define UNIQUE(x)   sort(all(x)), x.erase(unique(all(x)), x.end()), x.shrink_to_fit()
template <typename T, typename U> T ceil(T x, U y) {return (x > 0 ? (x + y - 1) / y : x / y);}
template <typename T, typename U> T floor(T x, U y) {return (x > 0 ? x / y : (x - y + 1) / y);}
const int N = 1e5 + 10;
void solve()
{
    int n, m;
    cin >> n;
    vector<int> v(n);
    vector<int> two, one, three;
    two.push_back(-1);
    for (int i = 0; i < n; i++)
    {
        cin >> v[i];
        if (v[i] == 2)
        {
            two.push_back(i);
        }
        if (v[i] == 1)
        {
            one.push_back(i);
        }
    }
    two.push_back(n);
    reverse(all(v));
    for (int i = 0; i < n; i++)
    {
        if (v[i] == 3)
        {
            three.push_back(i);
        }
    }
    int mx = 0;
    for (int i = 0; i + 1 < two.size(); i++)
    {
        int l = two[i], r = two[i + 1];
        auto it = lower_bound(all(one), l);
        if (it == one.end())continue;
        int left = 0, right = 0;
        if (*it > l && *it < r)
        {
            left = *it;
        }
        int nr = n - r - 1;
        auto it1 = lower_bound(all(three), nr);
        if (it1 == three.end())continue;
        int idx = n - *it1 - 1;
        if (idx > l && idx < r)
        {
            right = idx;
        }
        mx = max(mx, right - left + 1);
    }
    cout << mx << endl;
}
int32_t main()
{
    Abid_52;
    int t = 1;
    cin >> t;
    for (int tc = 1; tc <= t; ++tc)
    {
        // cout << "Case " << tc << ": ";
        solve();
    }
}