Write a question about the following article: Svinhufvud's Senate introduced Finland's Declaration of Independence on 4 December 1917 and Parliament adopted it on 6 December. The social democrats voted against the Senate's proposal, while presenting an alternative declaration of sovereignty. The establishment of an independent state was not a guaranteed conclusion for the small Finnish nation. Recognition by Russia and other great powers was essential; Svinhufvud accepted that he had to negotiate with Lenin for the acknowledgement. The socialists, having been reluctant to enter talks with the Russian leadership in July 1917, sent two delegations to Petrograd to request that Lenin approve Finnish sovereignty. In December 1917, Lenin was under intense pressure from the Germans to conclude peace negotiations at Brest-Litovsk and the Bolsheviks' rule was in crisis, with an inexperienced administration and the demoralised army facing powerful political and military opponents. Lenin calculated that the Bolsheviks could fight for central parts of Russia but had to give up some peripheral territories, including Finland in the geopolitically less important north-western corner. As a result, Svinhufvud's delegation won Lenin's concession of sovereignty on 31 December 1917. By the beginning of the Civil War, Austria-Hungary, Denmark, France, Germany, Greece, Norway, Sweden and Switzerland had recognised Finnish independence. The United Kingdom and United States did not approve it; they waited and monitored the relations between Finland and Germany , hoping to override Lenin's regime and to get Russia back into the war against the German Empire. In turn, the Germans hastened Finland's separation from Russia so as to move the country to within their sphere of influence.
How many days passed between Finland's Declaration of Independence and Lenin's concession?