1. An image forming system for obtaining printed material with facilitating material for accessing to specific pages or areas of the printed material, the image forming system comprising: a first feeding section for feeding a recording sheet; a second feeding section for feeding the facilitating material; a first input section for obtaining a number of sheets constituting one set of the facilitating material loaded on the second feeding section; a second input section for receiving position information with regard to a position where the facilitating material is added into the printed material; a transmitting section for transmitting print data; a printing section for recording an image on the recording sheet based on the print data; wherein the second feeding section feeds the facilitating material based on the position information, and the image forming system guides an input of the position information based on the number of sheets constituting one set of the facilitating material; and wherein the image forming system further comprises: a display section for displaying input areas for the position information, wherein a number of the input areas is equal to an integral multiple of the number of the sheets constituting one set of the facilitating material; a judging section which judges whether a number of positions of the position information set in the input areas is equal to the integral multiple of the number of sheets constituting one set of the facilitating material, after the position information is set in the input areas; and an urging section which urges a user to rework the input operation of the position information, when the number of positions of the position information set in the input areas is not equal to the integral multiple of the number of sheets constituting one set of the facilitating material, wherein the urging section displays a rework message and the input areas for the position information, and a number of the input areas is equal to at least the number of sheets constituting one set of the facilitating material lastly obtained by the first input section.