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

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

    string s, p,m="";
    cin >> s >> p;
    for(int i=0;i<n;i++){
        if((s[i]<=p[i] and i==0)){
            m+=s[i];
         

        }
        else if(p[i]<=s[i] and i==0){
            m+=p[i];
             //  cout<<m[i];
        }
        else if(i>0 and s[i]<=p[i] and m[i-1]<=s[i])m+=s[i];
        else if(i>0 and p[i]<=s[i] and m[i-1]<=s[i])m+=s[i];
    }

if(m.size()!=n)cout<<"No\n";
else 
    cout<<"Yes\n";
}

int main()
{

    int t;
    cin >> t;
    while (t--)
    {
        error();
    }
}