758 B | 758 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
BLANK = " "
#inp = input
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
a, *a_l = mii()
b, *b_l = mii()
cnt = [['A', 0, 0, 0, 0], ['B', 0, 0, 0, 0]]
for i in a_l:
cnt[0][i] += 1
for j in b_l:
cnt[1][j] += 1
cnt.sort(key = lambda t: (-t[4], -t[3], -t[2], -t[1]))
if cnt[0][1:] == cnt[1][1:]:
print("D")
else:
print(cnt[0][0])
if __name__ == "__main__":
tc = ii()
for t in range(1, tc+1):
ret = solve()