#include<bits/stdc++.h>
using namespace std;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T;
    cin>>T;
    while(T--)
    {
        int N;
        string S;
        cin>>N>>S;
        int P=0,K=0;
        for(int i=0;i<N;i++)
        {
            if(S[i]=='P')
            {
                P++;
                while(i+1<N&&S[i+1]=='P')i++;
            }
            else if(S[i]=='K')
            {
                K++;
                while(i+1<N&&S[i+1]=='K')i++;
            }
        }
        cout<<(P>K?'P':'K')<<'\n';
    }
}