class Heap
	require 'forwardable'
	extend Forwardable

	def initialize
		@array = []
		@index = {}
	end

	def add(obj, key)
		@array << [obj, key]
		@index[obj] = @array.size - 1
		lift_up(@array.size - 1)
	end

	def swap(i, j)
		u = @array[i]
		v = @array[j]
		@index[u[0]], @index[v[0]] = j, i
		@array[i], @array[j] = v, u
	end

	def lift_up(i)
		return if i == 0
		j = (i - 1) / 2
		if (@array[i][1] <=> @array[j][1]) < 0
			swap(i, j)
			lift_up(j)
		end
	end

	def del_min
		raise "heap is empty!" if empty?
		min = @array[0]
		if size > 1
			swap(0, @array.size-1)
			@array.pop
			lift_down(0)
		else
			@array.pop
		end
		@index.delete(min[0])
		min
	end

	def inc_key(obj, diff)
		i = @index[obj]
		@array[i][1] += diff
		lift_down(i)
	end

	def dec_key(obj, diff)
		i = @index[obj]
		@array[i][1] -= diff
		lift_up(i)
	end

	def update_key(obj, new_key)
		i = @index[obj]
		return unless i
		return if (new_key <=> @array[i][1]) >= 0
		@array[i][1] = new_key
		lift_up(i)
	end

	def min_obj
		@array[0][0]
	end

	def min_key
		@array[0][1]
	end

	def lift_down(i)
		j = 2 * i + 1
		k = j + 1
		if k >= size
			return if j >= size
			if (@array[i][1] <=> @array[j][1]) > 0
				swap(i, j)
				lift_down(j)
			end
		else
			l = ((@array[j][1] <=> @array[k][1]) < 0 ? j : k)
			if (@array[i][1] <=> @array[l][1]) > 0
				swap(i, l)
				lift_down(l)
			end
		end
	end

	def include?(obj)
		@index.include?(obj)
	end

	def_delegators :@array, :empty?, :size
end

dij = [
	[-1, 0],
	[0, 1],
	[1, 0],
	[0, -1],
]

loop do
	h, w, n = gets.split.map(&:to_i)
	break if h == 0
	commands = gets.chomp
	a = (0..h-1).map { gets.chomp.split("") }

	si, sj, gi, gj = nil
	(0..h-1).each do |i|
		(0..w-1).each do |j|
			if a[i][j] == ?S
				si, sj = i, j
			end
			if a[i][j] == ?G
				gi, gj = i, j
			end
		end
	end

	pq = Heap.new

	i, j = si, sj
	loop do
		pq.add([i, j, 0], 0)
		i -= 1
		break if i < 0 || a[i][j] == ?#
	end

	min_command = {}
	loop do
		u, c = pq.del_min
		min_command[u] = c
		i, j, dir = u
		if i == gi && j == gj
			break
		end

		rest_dir = (0..3).to_a - [dir]
		(c..commands.size-1).each do |k|
			dir += 1 if commands[k] == ?R
			dir -= 1 if commands[k] == ?L
			dir %= 4
			next if ! rest_dir.include?(dir)
			rest_dir.delete(dir)

			di, dj = dij[dir]
			step = 1
			loop do
				new_i, new_j = i + step * di, j + step * dj
				break if new_i < 0 || new_i >= a.size
				break if new_j < 0 || new_j >= a[0].size
				break if a[new_i][new_j] == ?#
				v = [new_i, new_j, k+1]

				next if min_command[v]
				if pq.include?(v)
					pq.update_key(v, k+1)
				else
					pq.add(v, k+1)
				end
				step += 1
			end
			
			break if rest_dir.empty?
		end
		break if pq.empty?
	end

	if (0..3).any? {|d| min_command[[gi, gj, d]]}
		puts 'Yes'
	else
		puts 'No'
	end
end