local n, k = io.read("*n", "*n")
local a = {}
for i = 1, n do a[i] = io.read("*n") end
local t = {}
for i = 1, n do t[i] = "B" end
local idx = {}
for i = 1, n do
  a[i] = a[i] - io.read("*n")
  idx[i] = i
end
table.sort(idx, function(x, y) return a[x] > a[y] end)
for i = 1, k do
  t[idx[i]] = "A"
end
print(table.concat(t))