#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e9+7;
const ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ii,ll>
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///Training
int main(void){
ll t;
cin>>t;
while(t--){
ll n;
cin>>n;
ll arr[n];
vll a[2];
ll posa = 0;
bool b[n+5] = {0};
f(i,0,n){
cin>>arr[i];
if(i < n/2 && arr[i] > n/2){
posa++;
b[i+1] = true;
}
arr[i] = min(arr[i],n + 1 - arr[i]);
a[i >= n/2].pb(arr[i]);
}
reverse(all(a[1]));
ll res = n / 2;
bool v[n+5] = {0};
f(i,0,n/2){
if(!v[i+1]){
res--;
ll posoi = 0;
ll pos = i+1;
while(!v[pos]){
v[pos] = true;
posoi += b[pos];
pos = arr[pos - 1];
}
if(posoi % 2 == 1){
res++;
}
}
}
if(a[0] == a[1] && (posa % 2 == 0)){
cout<<res<<" ";
cout<<"0\n";
}
else{
cout<<"-1\n";
}
}
}
