#include using namespace std; using ll = long long; const ll MOD = 1000000007; using P = pair; #define rep(i, n) for(int i = 0; i < n; i++) #define all(x) (x).begin(),(x).end() int main(){ int t; cin >> t; rep(i,t){ int n; bool ans = true; cin >> n; vector a(2*n); vector> ad(n); rep(j,2*n){ cin >> a[j]; a[j]--; ad[a[j]].push_back(j); if(ad[a[j]].size() > 2) ans = false; } if(!ans){ cout << "No" << endl; continue; } rep(j,n+1){ ans = true; vector acopy = a; if(j