Polish poster, no idea what year it’s from but judging from the abscense of the Yugoslav flag and the presence of the Korean flag I’m assuming it’s from after 1948 and before 1956, because you know.

The 3 blue and 2 red flags with no markings confuse me - the red flags can be excused for symbolising socialism, but I don’t know what the blue flags symbolise.

PS. Am I supposed to tag the post with the language of the poster or the contents I write in here?