import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (1, 0), (0, -1), (-1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = 1 << 63
# md = 998244353
md = 10**9+7

n, k = LI()
aa = LI()
bb = LI()

di = []
for i, (a, b) in enumerate(zip(aa, bb)):
    di.append((a-b, i))

di.sort(key=lambda x: -x[0])
ans = [1]*n
for d, i in di[:k]: ans[i] = 0

print("".join("AB"[i] for i in ans))