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The four-day event in Valladolid in Spain gathers 3,500 of the best puzzlers, working individually or in teams, for the chance to be crowned champion.
Updated:
The four-day event in Valladolid in Spain gathers 3,500 of the best puzzlers, working individually or in teams, for the chance to be crowned champion.
A recently published study sheds light on the logic behind the tricky door policy of …