// LUOGU_RID: 98877933
#include<bits/stdc++.h>
using namespace std;
const int MAXN=2022;
int n,a[MAXN];
vector <int> ans;
inline int find(int x) {
	for(int i=1;i<=n;++i) if(a[i]==x) return i;
	return 0;
}
inline void oper(int x) {
	ans.push_back(x);
	reverse(a+1,a+x+1);
}
inline void solve() {
	ans.clear();
	scanf("%d",&n);
	for(int i=1;i<=n;++i) scanf("%d",&a[i]);
	for(int i=1;i<=n;++i) {
		if(i%2!=a[i]%2) {
			puts("-1");
			return ;
		}
	}
	for(int i=n;i>=3;i-=2) {
		int x=find(i);
		oper(x);
		int y=find(i-1);
		oper(y-1),oper(y+1),oper(3),oper(i);
	}
	printf("%d\n",(int)ans.size());
	for(int i:ans) printf("%d ",i);
	puts("");
}
signed main() {
	int T;
	scanf("%d",&T);
	while(T--) solve();
	return 0;
}