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

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

    string a, b; cin >> a >> b;
    string c;
    c.push_back(min(a[0], b[0]));
    for(int i = 1; i < n; i++){
        if(a[i] >= c.back() && b[i] >= c.back()){
            c.push_back(min(a[i], b[i]));
        }
        else if(a[i] >= c.back()){
            c.push_back(a[i]);
        }
        else if(b[i] >= c.back()){
            c.push_back(b[i]);
        }
        else{
           cout << "No\n";
            return;
        }
    }
    cout << "Yes\n";

}
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
	int t; cin >> t;

	while(t--){
        solve();
	}
}