Piano Sonata No. 16 in C Major, K. 545 "Sonata facile" - I. 快板 [C大调第16号钢琴奏鸣曲，K. 545 “单纯的奏鸣曲”] (C大调第16号钢琴奏鸣曲，K. 545 “单纯的奏鸣曲”)