HAVANA: Pope Francis warned the Colombian government and FARC rebels Sunday that failure is not an option in their ongoing negotiations to end a conflict that has burned for more than half a century. Speaking at the end of mass during his visit to the Cuban capital, where the two sides have been negotiating, the Argentine pontiff called on the leftist guerrillas and the government to achieve “definitive reconciliation,” warning: “We do not have the right to allow ourselves yet another failure.”