#include<bits/stdc++.h>

using namespace std;

int p[32];

int main()
{
	int t;
	cin >> t;
	
	while(t--)
	{
		int n;
		cin >> n;
		char v;
		memset(p, 0, sizeof(p));
		
		while(n--)
		{
			string a;
			char s;
			string c;
			cin >> a >> s >> c;
			
			if(c[0] == 'a')
			{
				p[s-65]++;
			}
		
			int max = 0;
	
			for(int i = 0 ; i < 32 ; i++)
			{
				if(p[i] > max)
				{
					max = p[i];
					v = i + 65;
				}
			}
		
		}
		cout << v << endl;
	}
	return 0;
}