#include <bits/stdc++.h>
using namespace std;
int main()
{
    int t; cin>>t;
    up:
    while (t--)
    {
        int n; cin>>n;
        string s,ss;
        cin>>s>>ss;
        string ans;
        ans.push_back(min(s[0],ss[0]));
        for(int i=1;i<n; i++){
           
          if(min(s[i],ss[i])>=ans[i-1]){
            ans.push_back(min(s[i],ss[i]));
          }
          else if(max(s[i],ss[i])>=ans[i-1]){
            ans.push_back(max(s[i],ss[i]));
          }
          else{
            cout<<"No"<<endl;
            goto up;
          }
        }
        cout<<"Yes"<<endl;
        /* code */
    }
    
}