T = int(input())
for _ in range(T):
    N = int(input())
    S = input().strip()
    cntK = 0
    cntP = 0
    flag = 0
    for i in range(N):
        if S[i]=="K" and flag!="K":
            flag = "K"
            cntK += 1
        elif S[i]=="P" and flag!="P":
            flag = "P"
            cntP += 1
        elif S[i]=="-":
            flag = 0
    if cntK>=cntP:
        print("K")
    else:
        print("P")