This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "bits/stdc++.h"
using namespace std;
#define ar array
typedef long long ll;
void solve(){
int n; cin>>n;
vector<int> a(n);
for(int i=0;i<n;i++) cin>>a[i];
vector<int> pos(n);
for(int i=0;i<n;i++) pos[--a[i]] = i;
vector<ar<int, 2>> res;
auto add = [&](int i, int j){
int i_ = n - i - 1, j_ = n - j - 1;
assert(j != i_);
swap(a[i], a[j]);
swap(pos[a[i]], pos[a[j]]);
res.push_back({i, j});
swap(a[i_], a[j_]);
swap(pos[a[i_]], pos[a[j_]]);
};
for(int i=0;i<n/2;i++){
if(a[i] == i) continue;
int j = pos[i];
if(j < n/2){
add(i, j);
} else {
if(n - j - 1 < i){
cout<<-1<<"\n";
return;
}
if(n - j - 1 == i){
if(i + 1 == j){
cout<<-1<<"\n";
return;
}
add(i, i + 1);
add(i, pos[i]);
} else {
add(i, j);
}
}
}
cout<<(int)res.size()<<" "<<(int)res.size()<<"\n";
for(auto x : res) cout<<x[0] + 1<<" "<<x[1] + 1<<"\n";
}
signed main(){
ios::sync_with_stdio(0); cin.tie(0);
int t; cin>>t;
while(t--){
solve();
}
}
/*
10
4 9 6 3 1 ' 10 8 5 2 7
1 9 6 3 4 ' 7 8 5 2 10
1 2 3 4 5 ' 6 7 8 9 10
*/
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