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

#define int         long long






void solve() {
    int n;          cin >> n;

    string s, t;        cin >> s >> t;

    string vlo;
    bool ok = 1;
    char pre = min(s[0], t[0]);

    cerr << pre << '\n';

    for (int i = 1; i < n; i++) {
        char curMin= min(s[i], t[i]);
        char curMax = max(s[i], t[i]);

        cerr << curMax << ' ' << curMin << ' ' << pre << '\n';

        if (curMin >= pre) {
            pre = curMin;
            continue;
        }else if (curMax >= pre) {
            pre = curMax;
            continue;
        }

        ok = 0;
    }

    
    cout << ((ok) ? "Yes\n" : "No\n");
}



signed main() {
    int tt;     cin >> tt;

    while (tt--) 
        solve();
    
}