local n, m = io.read("*n", "*n", "*l")
local w, a, c = {}, {}, {}
local s = io.read()
for i = 1, #s do
  local b = s:sub(i, i)
  if b == "W" then
    table.insert(w, i)
  elseif b == "A" then
    table.insert(a, i)
  else
    table.insert(c, i)
  end
end
for i = n, 1, -1 do
  if a[m + i] < w[i] then
    print("No") os.exit()
  end
end
for i = 1, m do
  if c[i] < a[i] then
    print("No") os.exit()
  end
end
print("Yes")