#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
#define all(v) v.begin(),v.end()
#define nl "\n"
#define FIO \
    ios_base::sync_with_stdio(false);\
    cin.tie(NULL);\
    cout.tie(NULL);

void solve()
{
    ll n;   cin>>n;
    string a,b; cin>>a>>b;

    string s="A";
    for(ll i=0;i<n;i++)
    {
        if(a[i]<s.back() && b[i]<s.back())
        {
            cout<<"No"<<nl;
            return;
        }
        else if(a[i]>=s.back() && b[i]>=s.back())
        {
            s.push_back(min(a[i],b[i]));
        }
        else if(a[i]>=s.back()) s.push_back(a[i]);  
        else if(b[i]>=s.back()) s.push_back(b[i]); 
    }
    if(is_sorted(all(s)))    cout<<"Yes"<<nl;
    else cout<<"No"<<nl;
}

int32_t main()
{
    ll t=1;
    cin>>t;
    for(ll i=1;i<=t;i++)
    {
        // cout<<"Case "<<i<<": ";
        solve();
    }
}