#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
 
using namespace std;
 
#define ll long long
#define nl "\n"
const int mod = (int) 1000000007;
const int N = (int) 1000006;
#define INF 2147483647
#define drop(s) cout << #s << "\n"
#define ext exit(0)
#define vtr vector <int>
#define st set <int>
#define mp map <int, int>
#define mem(arr, n) memset(arr, n, sizeof(arr))
#define sz(x) (int)x.size()
#define pb push_back
#define fs first
#define sc second
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define fr(i, a, b) for (int i = (a); i < (int)(b); ++i)
#define takeinp(a, n) for(int i=0; i<n; i++) cin>>a[i]
#define print(a, n) for(int i=0; i<n; i++) cout<<a[i]<<" "; cout<<"\n";
#define gcd(x, y) __gcd(x,y)
#define lcm(a, b) a*(b/gcd(a, b))
#define setBit(n) __builtin_popcount(n)
#define secIndxSorter(p, n) sort(p, p+n,[](const pair<int, int>& lhs, const pair<int, int>& rhs) {return lhs.second < rhs.second;});
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define optimize ios_base::sync_with_stdio(false); cin.tie(0);
struct{
    template<class T> operator T() {
        T x;
        cin >> x;
        return x;
    }
}in;
 
void onlineJudge(){
	#ifndef ONLINE_JUDGE
		freopen("input.txt","r",stdin); 
		freopen("output.txt","w",stdout);  
	#endif
}
 
void solve() {
	int n = in;
	string s = in, dir = in;
	string ans = "";
 
 
	for(int i=0; i<n; i++) {
		int indx = i+1;
		indx %= 26;
 
		if(dir[i]=='U') {
			int x = indx + s[i];
			if(x<=122) {
				ans += x;
			}
			else {
				x -= 122;
				x += 96;
				ans += x;
			}
		}
		else {
 
			int x = s[i] - indx;
			if(x>=97) {
				ans += x;
			}
			else {
				x = 97 - x;
				// cout<<"x is "<<x<<nl;
				x -= 123;
				ans += x;
			}
		}
	}
 
	cout<<ans<<nl;
}
 
int main() {
 
 
    optimize;
 
    int T; cin>>T;
    for(int i=1; i<=T; i++) {
        solve();
    }
 
    return 0;
}