for _ in range(int(input())):
    n = int(input()); s = input()+"-"; k = p = 0
    for i in range(n):
        if s[i]=="K" and s[i-1]!="K": k += 1
        if s[i]=="P" and s[i-1]!="P": p += 1
    print("K" if k>=p else "P")