import sys
input = sys.stdin.readline
for i in range(int(input())):
    n = int(input())
    s = list(input().rstrip())
    def rle(s):
        res = []
        for j in s:
            if not res or res[-1][0] != j:
                res.append([j,1])
            else:
                res[-1][1] += 1
        return res
    p,k = 0,0
    x = rle(s)
    for j,z in x:
        if j == 'P':
            p += 1
        if j == 'K':
            k += 1
    if p > k:
        print('P')
    else:
        print('K')