#include <bits/stdc++.h>
using namespace std;

int isSorted(string st, int n)
{
    if (n == 1)
    {
        return 1;
    }

    for (int i = 0; i < n - 1; i++)
    {
        if (st[i] > st[i + 1])
        {
            return 0;
        }
    }

    return 1;
}






int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        cin >> n;
        string s1, s2;
        cin >> s1 >> s2;


        string temps1 = s1, temps2 = s2;
        int flag = 1;
        for(int i = 0; i < n - 1; i++) {
             
            if(s1[i] > s1[i + 1]) {
                swap(temps1[i], temps2[i]);

                if(isSorted(temps1, n) || isSorted(temps2, n)) {
                    cout << "Yes" << endl;
                    flag = 0;
                    break;
                }
                
            }
        }

        temps1 = s1, temps2 = s2;
        for(int i = 0; i < n - 1; i++) {
             
            if(s2[i] > s2[i + 1]) {
                swap(temps2[i], temps1[i]);

                if(isSorted(temps2, n) || isSorted(temps1, n)) {
                    cout << "Yes" << endl;
                    flag = 0;
                    break;
                }
                
            }
        }





        if(flag) {
            cout << "No" << endl;
        }

       
    }
}