The present invention relates to an input system for feeding one-up sheets from a paper web to a high speed mass mailing inserter system. The input system includes a feeding module for supplying a paper web having two web portions in side-by-side relationship. A merging module is located downstream in the path of travel from the feeding module and is operational to feed the two web portions in an upper-lower relationship so as to reorient the paper web from the side-by-side relationship to an upper-lower relationship. A separating module is located downstream in the path of travel from the merging module and is operational to receive the paper web in the upper-lower relationship and separate the paper web into individual two-up sheets. In order to separate the two-up sheets into one-up sheets, a stacking module is located downstream in the path of travel from the separating module and is configured to receive the two-up sheets, stack the two-up sheets and individually feed one-up sheets from the stack.