sentences:  Liszt's two concertos, however, are unconventional, in that the first concerto's five sections are connected both formally and thematically, and the second utilizes a still freer sectional structure.The first concerto in particular shows the influence of such continuous composite forms as those of Weber's Konzertstuck and Schubert's Wanderer Fantasy.The virtuosity required by all these concertos was facilitated by—and helped to spur—technical developments in the instruments themselves.