Each euro zone country will have to prepare a contingency plan for the eventuality of Greece leaving the single currency, euro zone sources said on Wednesday. Officials reached the consensus on Monday afternoon during an hour-long teleconference of the Eurogroup Working Group (EWG). As well as confirmation from three euro zone officials, Reuters has seen a memo drawn up by one member state detailing some of the elements that euro zone countries should consider. The EWG consists of officials who prepare meetings of finance ministers and also form the board of the temporary bailout fund, the European Financial Stability Facility (EFSF). It consists mostly of deputy finance ministers and senior treasury officials. "The EWG agreed that each euro zone country should prepare a contingency plan, individually, for the potential consequences of a Greek exit from the euro," said one euro zone official familiar with what was discussed on the call. ...