#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)

using std::cin;
using std::cout;
using std::map;

int main() {
	int t;
	cin >> t;
	
	while (t--) {
		int n;
		cin >> n;
		n *= 2;
		bool ok = true;
		map<int, int> mp;
		rep(i, n) {
			int a; cin >> a;
			if (mp.count(a) and i - mp[a] <= 1) ok = false;
			mp[a] = i;
		}
		puts(ok ? "Yes" : "No");
	}
	
	return 0;
}