直接按照题意模拟即可

#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <cstdio>
#include <unordered_map>
#include <queue>
#include <deque>
#include <cmath>
#include <set>
#include <stack>
#include <map>
using namespace std;
//#define int long long
signed main()
{
	int t;
	scanf("%d",&t);
	while(t--)
	{
		int n;
		scanf("%d",&n);
		string s1;
		cin >> s1;
		int m;
		scanf("%d",&m);
		string s2;
		cin >> s2;
		string ss=s1;
		string k;
		cin >> k;
		int len=k.length();
		for(int i=0;i<len;i++)
		{
			if(k[i]=='D')
			{
				ss=ss+s2[i];
			}
			else
				ss=s2[i]+ss;
		}
		cout << ss << endl;
	}	
	return 0;
}