#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

void solve() {
    int T;
    cin >> T;
    
    while (T--) {
        int n;
        cin >> n;
        
        vector<int> A(n), B(n);
        for (int i = 0; i < n; ++i) cin >> A[i];
        for (int i = 0; i < n; ++i) cin >> B[i];
        
        // 检查 A 和 B 是否可以通过排序一致
        vector<int> sortedA = A, sortedB = B;
        sort(sortedA.begin(), sortedA.end());
        sort(sortedB.begin(), sortedB.end());
        
        if (sortedA != sortedB) {
            cout << -1 << endl;
            continue;
        }
        
        vector<pair<int, int>> swaps;
        
        // 通过交换将 A 转换为 B
        for (int i = 0; i < n; ++i) {
            if (A[i] != B[i]) {
                for (int j = i + 1; j < n; ++j) {
                    if (A[j] == B[i]) {
                        // 将 A[j] 移动到 A[i] 位置
                        for (int k = j; k > i; --k) {
                            if (A[k] < A[k - 1]) {
                                cout << -1 << endl;
                                break;
                            }
                            swaps.push_back({k, k - 1});
                            swap(A[k], A[k - 1]);
                        }
                        break;
                    }
                }
            }
        }
        
        // 输出结果
        cout << swaps.size() << endl;
        for (const auto &p : swaps) {
            cout << p.first + 1 << " " << p.second + 1 << endl;
        }
    }
}

int main() {
    solve();
    return 0;
}