import java.io.*;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int t = Integer.parseInt(br.readLine());
		PrintWriter pw = new PrintWriter(System.out);
		for (int z = 0; z < t; z++) {
			int n = Integer.parseInt(br.readLine());
			char[] s = br.readLine().toCharArray();

			int k = 0;
			int p = 0;
			char pre = 'a';
			for (int i = 0; i < n; i++) {
				if (s[i] != pre) {
					if (s[i] =='K') k++;
					if (s[i] =='P') p++;
					pre = s[i];
				}
			}
			if (k >= p) {
				pw.println("K");
			} else {
				pw.println("P");
			}
		}
		pw.flush();
		br.close();
	}
}