// compile: make data
// run: ./data < data.in
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#include <debug/codeforces.h>
#define debug(x...) _debug_print(#x, x);
#else
#define debug(x...) {};
#endif
template<typename...Args> void print_(Args...args){((cout<<args<<" "),...)<<endl;}
#define rep(i,a,b) for(int i=(a);i<(int)(b);++i)
#define sz(v) ((int)(v).size())
#define print(...) print_(__VA_ARGS__);
#define INTMAX (int)(9223372036854775807)
#define INF (int)(1152921504606846976)
#define double long double
#define int long long
#define MAXN 200010

void solve() {
    int n; cin >> n;
    vector<int> a(2*n+1), b(2*n+1);
    int pre = 0, num = 0;
    rep(i, 0, n) {
        int x; cin >> x;
        if (x != pre) a[pre] = max(a[pre], num), pre = x, num = 1;
        else ++num;
    }
    a[pre] = max(a[pre], num);
    pre = 0, num = 0;
    rep(i, 0, n) {
        int x; cin >> x;
        if (x != pre) b[pre] = max(b[pre], num), pre = x, num = 1;
        else ++num;
    }
    b[pre] = max(b[pre], num);
    int ans = 0;
    rep(i, 0, 2*n+1) {
        ans = max(ans, a[i] + b[i]);
    }
    cout << ans << endl;
}

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

    int _; cin >> _;
    while (_--) solve();

    return 0;
}