n, k = read_line.split.map(&.to_i)
cs = Array.new(n, -1)
k.times do
  a, c = read_line.split
  cs[a.to_i - 1] = "RGB".index(c).not_nil!
end
ans = [] of Int32
cnt = [0, 0, 0]
n.times do |i|
  min = 3.times.min_by { |i| cnt[i] }
  case i % 3
  when 0
    ans << (cs[i] == -1 ? 0 : cs[i])
  when 1
    if cs[i] == -1
      ans << min
    else
      ans << (ans[-1] == cs[i] ? min : cs[i])
    end
  when 2
    ans << min
  end
  cnt[ans[-1]] += 1
end
puts ans.map { |i| "RGB"[i] }.join