#include<bits/stdc++.h>
using namespace std;
const int N=2e5+10;
char a[N],b[N],c[N];
int n;
bool judge(){
	int cnt=0;
	for(int i=1;i<=n;i++)	if(c[i]=='#')	cnt++;
	if(cnt==0)	return false;
	for(int i=2;i<=n;i++){
		if(a[i-1]=='#'&&a[i]=='#'&&c[i-1]=='#'&&c[i]=='.')	return false;
		if(b[i-1]=='#'&&b[i]=='#'&&c[i-1]=='#'&&c[i]=='.')	return false;
	}
	return true;
}
void solve(){
	int cnt=0;
	cin>>n;
	cin>>a+1>>b+1;
	for(int i=1;i<=n;i++)
		if(a[i]==b[i])	cnt++;
	if(cnt==0||cnt==n){
		cout<<"Yes\n";
		cout<<a+1<<'\n';
		cout<<a+1<<'\n';
		cout<<a+1<<'\n';
		cout<<a+1<<'\n';
		cout<<b+1<<'\n';
		cout<<b+1<<'\n';
		cout<<b+1<<'\n';
		return ;
	}
	if(a[1]=='.'&&b[1]=='.')	c[1]='#';
	else c[1]='.';
	for(int i=2;i<=n;i++){
		if(a[i]=='.'&&b[i]=='.')	c[i]='#';
		else if(a[i]=='#'&&b[i]=='#')	c[i]='.';
		else{
			if(a[i-1]==b[i-1])	c[i]='.';
			else{
				if(a[i-1]==c[i-1])	c[i]=a[i];
				else c[i]=b[i];
			}
		}
	}
	if(judge()){
		cout<<"Yes\n";
		cout<<a+1<<'\n';
		cout<<a+1<<'\n';
		cout<<a+1<<'\n';
		cout<<c+1<<'\n';
		cout<<b+1<<'\n';
		cout<<b+1<<'\n';
		cout<<b+1<<'\n';
	}
	else cout<<"No\n";
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int T;
	cin>>T;
	while(T--)	solve();
	return 0;
} 
/*
4
4
#..#
.##.
5
##.#.
.#.##
6
######
.####.
27
.######.######.####.#.#####
.####...####..#.......#####

1
10
.##.###.##
##.#####.#
 */